rules of department of natural resources · 2019-01-28 · 10 csr 60-4.022 revised total coliform...

CODE OF STATE REGULATIONS 1JOHN R. ASHCROFT (1/29/19)Secretary of State

Rules ofDepartment of Natural Resources

Division 60—Safe Drinking Water CommissionChapter 4—Contaminant Levels and Monitoring

Title Page

10 CSR 60-4.010 Maximum Contaminant Levels and Monitoring Requirements .........................3

10 CSR 60-4.020 Maximum Microbiological Contaminant Levels and MonitoringRequirements (Rescinded September 30, 2018) ..........................................3

10 CSR 60-4.022 Revised Total Coliform Rule..................................................................4

10 CSR 60-4.025 Ground Water Rule Monitoring and Treatment Technique Requirements ...........12

10 CSR 60-4.030 Maximum Inorganic Chemical Contaminant Levels, Action Levelsand Monitoring Requirements..............................................................17

10 CSR 60-4.040 Maximum Synthetic Organic Chemical Contaminant Levels andMonitoring Requirements...................................................................20

10 CSR 60-4.050 Maximum Turbidity Levels and Monitoring Requirements and FilterBackwash Recycling..........................................................................21

10 CSR 60-4.052 Source Water Monitoring and Enhanced Treatment Requirements ...................22

10 CSR 60-4.055 Disinfection Requirements...................................................................43

10 CSR 60-4.060 Maximum Radionuclide Contaminant Levels and Monitoring Requirements.......46

10 CSR 60-4.070 Secondary Contaminant Levels and Monitoring Requirements .......................49

10 CSR 60-4.080 Operational Monitoring ......................................................................49

10 CSR 60-4.090 Maximum Contaminant Levels and Monitoring Requirementsfor Disinfection By-Products (Rescinded February 28, 2019) ........................53

10 CSR 60-4.092 Initial Distribution System Evaluation (Rescinded September 30, 2018) ............53

10 CSR 60-4.094 Disinfectant Residuals, Disinfection Byproduct Precursors and the Stage 2 Disinfectants/Disinfection Byproducts Rule ...................................53

10 CSR 60-4.100 Maximum Volatile Organic Chemical Contaminant Levels and Monitoring Requirements ...................................................................61

10 CSR 60-4.110 Special Monitoring for Unregulated Chemicals(Rescinded September 30, 2018) ..........................................................62

Title 10—DEPARTMENT OFNATURAL RESOURCES

Division 60—Safe Drinking WaterCommission

Chapter 4—Contaminant Levels andMonitoring

10 CSR 60-4.010 Maximum ContaminantLevels and Monitoring Requirements

PURPOSE: This rule establishes samplingand monitoring requirements for public watersystems and criteria for significant defienciesat surface water systems.

(1) The rules in this chapter contain maxi-mum contaminant levels (MCLs) permissiblein public water systems and describe associ-ated monitoring requirements. A supplier ofwater must collect or have collected samplesof the water and shall provide for analysis ofthese samples for designated contaminants.Nothing in this chapter shall preclude a dulydesignated representative of the departmentfrom taking samples or from using the resultsfrom the samples to determine compliance bya supplier of water with applicable provisionsof these rules.

(2) Laboratory services required by this chap-ter to determine contaminant levels are avail-able from the Department of NaturalResources (DNR) or the Department ofHealth according to the fee schedule set outin 10 CSR 60-16.030.

(A) Samples must be collected at no lessthan the required frequency and in accor-dance with schedules established by thedepartment when samples are submitted tothe DNR or the Department of Health labo-ratory for analysis.

(B) A supplier of water which submitssamples to the DNR or the Department ofHealth laboratory must collect and submitsamples using containers provided by thedepartment in accordance with the instruc-tions enclosed.

(C) A supplier of water not using the DNRor the Department of Health laboratory musthave the analysis done by a laboratory certi-fied by the department.

(3) Samples taken to determine compliancewith the requirements of this chapter shall betaken at representative points of the publicwater system, as approved by the department.The supplier of water shall provide satisfacto-ry sampling taps. Samples for microbiologi-cal analysis must be received in the labora-

tory for analysis within thirty (30) hours ofcollection.

(4) All analytical results must be accurate toat least the same number of significant fig-ures as the applicable MCL.

(5) All analyses must be consistent with themethods and procedures described in 10 CSR60-5.010 and 10 CSR 60-5.020. The resultsof all analyses must be used to determinecompliance with the MCLs unless the analyt-ical results are invalidated for technical rea-sons, such as obvious sampling errors.

(6) When a public water supply system sup-plies water to one (1) or more other publicwater supply systems, the department maymodify the monitoring requirements imposedby these rules to the extent that the intercon-nection of the systems justifies treating themas a single system for monitoring purposes.Any modified monitoring must be conductedpursuant to a schedule specified by thedepartment.

(7) Inspections and Sanitary Surveys ofSurface Water Systems.

(A) Sanitary surveys of all surface watersystems and systems using groundwater underthe direct influence of surface water will beconducted at least every three (3) years forcommunity systems and every five (5) yearsfor noncommunity systems. Sanitary surveyas used in this section (7) means an on-sitereview, under the supervision of an engineer,of the water source (identifying its sources ofcontamination using the results of sourcewater assessments where available), facilities,equipment, operation, maintenance, andmonitoring compliance, in order to evaluatethe adequacy of the system, its sources andoperations and the distribution of safe drink-ing water. It also includes a review of the dis-infection profile for systems that are requiredto comply with disinfection profiling require-ments.

(B) For community water systems deter-mined by the department to have no signifi-cant deficiencies (for example, defects orinadequacies that increase risk from water-borne disease, such as deficiencies involvingthe removal, inactivation or reintroduction ofpathogens or prevention or removal of chem-ical contamination) in two (2) consecutivesanitary surveys, the frequency of sanitarysurveys may be decreased to once every five(5) years. Upon finding a significant defi-ciency, the department may return the com-munity water system to the three (3)-yearschedule.

(C) Public water systems must respond inwriting to significant deficiencies outlined insanitary survey reports no later than forty-five (45) days after receipt of the report. Theresponse must indicate how and on whatschedule the system will address significantdeficiencies noted in the survey. Failure torespond within forty-five (45) days is a viola-tion. Public water systems shall take neces-sary steps to address significant deficienciesidentified in sanitary survey reports if suchdeficiencies are within the control of the pub-lic water system and its governing body.

(D) The department, at its discretion, mayconduct routine inspections of any publicwater system or make other necessary inspec-tions to determine compliance with theserules. If, after investigation, the departmentfinds that any public water system is incom-petently supervised, improperly operated,inadequate, of defective design or if the waterfails to meet standards established in 10 CSR60, the water supplier must implementchanges that may be required by the depart-ment.

(8) The provisions of this rule are declaredseverable. If any fee fixed by this rule is heldinvalid by a court of competent jurisdiction orby the Administrative Hearing Commission,the remaining provisions of this rule shallremain in full force and effect, unless other-wise determined by a court of competentjurisdiction or by the Administrative HearingCommission.

AUTHORITY: section 640.100, RSMo Supp.2003.* Original rule filed May 4, 1979,effective Sept. 14, 1979. Amended: FiledApril 14, 1981, effective Oct. 11, 1981.Amended: Filed Aug. 13, 1982, effective Jan.13, 1983. Amended: Filed June 2, 1988,effective Aug. 31, 1988. Amended: Filed Dec.4, 1990, effective July 8, 1991. Amended:Filed April 14, 1994, effective Nov. 30, 1994.Amended: Filed Dec. 15, 1999, effectiveSept. 1, 2000. Amended: Filed April 15,2003, effective Jan. 30, 2004.

*Original authority: 640.100, RSMo 1939, amended 1978,1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996, 1998,1999, 2002.

10 CSR 60-4.020 Maximum Microbiologi-cal Contaminant Levels and MonitoringRequirements(Rescinded September 30, 2018)

AUTHORITY: section 640.100, RSMo Supp.2014. Original rule filed May 4, 1979, effec-tive Sept. 14, 1979. Amended: Filed April 14,1981, effective Oct. 11, 1981. Rescinded andreadopted: Filed Dec. 4, 1990, effective July


Chapter 4—Contaminant Levels and Monitoring 10 CSR 60-4

8, 1991. Amended: Filed Feb. 1, 1996, effec-tive Oct. 30, 1996. Amended: Filed March17, 2003, effective Nov. 30, 2003. Amended:Filed Aug. 12, 2015, effective March 30,2016. Rescinded: Filed Dec. 29, 2017, effec-tive Sept. 30, 2018.

10 CSR 60-4.022 Revised Total ColiformRule

PURPOSE: The rule establishes samplingand monitoring requirements for public watersystems. The rule also establishes a maximumcontaminant level (MCL) for E. coli and usesE. coli and total coliforms to initiate a “findand fix” approach to address fecal contami-nation that could enter into the distributionsystem. It requires public water systems toperform assessments to identify sanitarydefects and subsequently take correctiveaction to correct them. The rule sets monitor-ing and treatment technique requirements forseasonal systems. The rule is based on therequirements in the federal Revised TotalColiform Rule found in subpart Y of 40 CFRpart 141.

(1) General Requirements and Applicability.(A) The provisions of this rule include both

maximum contaminant level (MCL) andtreatment technique requirements.

(B) Applicability. The provisions of thisrule apply to all public water systems.

(C) Violations of national primary drinkingwater regulations. Failure to comply with theapplicable requirements of this rule, includ-ing requirements established by the depart-ment pursuant to these provisions, is a viola-tion of the National Primary Drinking WaterRegulations.

(2) Analytical methods and laboratory certifi-cation.

(A) Analytical methodology. 1. The standard sample volume required

for analysis, regardless of analytical methodused, is one hundred milliliter (100 mL).

2. Systems need only determine the pres-ence or absence of total coliforms and E. coli;a determination of density is not required.

3. The time from sample collection toinitiation of test medium incubation may notexceed thirty (30) hours. Systems are encour-aged but not required to hold samples belowten degrees (10°) Celsius during transit.

4. If water having residual chlorine (mea-sured as free, combined, or total chlorine) isto be analyzed, sufficient sodium thiosulfate(Na2S2O3) must be added to the sample bottlebefore sterilization to neutralize any residualchlorine in the water sample. Dechlorinationprocedures are addressed in Section 9060A.2

of Standard Methods for the Examination ofWater and Wastewater (20th and 21st edi-tions).

5. Total coliform and E. coli analysesmust be conducted in accordance with one (1)of the analytical methods or alternative meth-ods incorporated by reference in 10 CSR 60-5.010(3).

(B) Laboratory Certification. Systemsmust have all compliance samples requiredunder this rule analyzed by a laboratory cer-tified by the Environmental ProtectionAgency (EPA) or the department to analyzedrinking water samples. The laboratory usedby the system must be certified for eachmethod (and associated contaminant(s)) usedfor compliance monitoring analyses underthis rule.

(3) General monitoring requirements for allpublic water systems.

(A) Sample siting plans. 1. Systems must develop a written sam-

ple siting plan that identifies sampling sitesand a sample collection schedule that are rep-resentative of water throughout the distribu-tion system. These plans are subject todepartment review and revision. Systemsmust collect total coliform samples accordingto the written sample siting plan. Monitoringrequired by sections (4)–(8) of this rule maytake place at a customer’s premise, dedicatedsampling station, or other designated compli-ance sampling location. Routine and repeatsample sites and any sampling points neces-sary to meet the requirements of 10 CSR 60-4.025 must be reflected in the sampling plan.

2. The minimum monitoring frequencyfor total coliforms is based on the populationserved by the system as defined in the chartin section (7) of this rule except that systemsusing surface water or ground water underthe direct influence of surface water or sys-tems practicing iron removal or lime soften-ing must collect at least five (5) samples permonth. Unless the department approves orspecifies in writing of a lesser frequencybased on population and system type asdefined in sections (4)–(7) of this rule, sys-tems must monitor each calendar month thatthe system provides water to the public anddetermine compliance with the MCL in sub-section (10)(A) of this rule for each month inwhich it is required to monitor. Systems mustcollect samples at regular time intervalsthroughout the month, except that systemsthat use only ground water and serve fourthousand nine hundred (4,900) or fewer peo-ple may collect all required samples on a sin-gle day if they are taken from different sites.

3. Systems must take at least the mini-mum number of required samples even if the

system has had an E. coli maximum contam-inant level (MCL) violation or has exceededthe coliform treatment technique triggers insubsection (9)(A) of this rule.

4. A system may conduct more compli-ance monitoring than is required by this ruleto investigate potential problems in the distri-bution system and use monitoring as a tool toassist in uncovering problems. A system maytake more than the minimum number ofrequired routine samples and must includethe results in calculating whether the coliformtreatment technique trigger in subparagraphs(9)(A)1.A.–B. of this rule has been exceededonly if the samples are taken in accordancewith the existing sample siting plan and arerepresentative of water throughout the distri-bution system.

5. Systems must identify repeat moni-toring locations in the sample siting plan.Unless the provisions of subparagraphs(3)(A)5.A. or B. of this rule are met, the sys-tem must collect at least one (1) repeat sam-ple from the sampling tap where the originaltotal coliform-positive sample was taken, andat least one (1) repeat sample at a tap withinfive (5) service connections upstream and atleast one (1) repeat sample at a tap withinfive (5) service connections downstream ofthe original sampling site. If a total coliform-positive sample is at the end of the distribu-tion system, or one (1) service connectionaway from the end of the distribution system,the system must still take all required repeatsamples. However, the department may allowan alternative sampling location instead of therequirement to collect at least one (1) repeatsample upstream or downstream of the origi-nal sampling site. Except as provided for insubparagraph (3)(A)5.B. of this rule, systemsrequired to conduct triggered source watermonitoring under 10 CSR 60–4.025(3)(A)must take ground water source sample(s) inaddition to repeat samples required under thisrule.

A. Systems may propose repeat mon-itoring locations to the department that thesystem believes to be representative of a path-way for contamination of the distribution sys-tem. A system may elect to specify eitheralternative fixed locations or criteria forselecting repeat sampling sites on a situation-al basis in a standard operating procedure(SOP) in its sample siting plan. The systemmust design its SOP to focus the repeat sam-ples at locations that best verify and deter-mine the extent of potential contamination ofthe distribution system area based on specificsituations. The department may modify theSOP or require alternative monitoring loca-tions as needed.

B. Ground water systems serving one

4 CODE OF STATE REGULATIONS (1/29/19) JOHN R. ASHCROFT

Secretary of State

10 CSR 60-4—DEPARTMENT OF NATURAL RESOURCES Division 60—Safe Drinking Water Commission

thousand (1,000) or fewer people may pro-pose repeat sampling locations to the depart-ment that differentiate potential source waterand distribution system contamination (e.g.,by sampling at entry points to the distributionsystem). A ground water system with a singlewell required to conduct triggered sourcewater monitoring may, with written depart-ment approval, take one (1) of its repeat sam-ples at the monitoring location required fortriggered source water monitoring under 10CSR 60-4.025(3)(A) if the system demon-strates to the department’s satisfaction thatthe sample siting plan remains representativeof water quality in the distribution system. Ifapproved by the department, the system mayuse that sample result to meet the monitoringrequirements in both 10 CSR 60-4.025(3)(A)and this section.

(I) If a repeat sample taken at themonitoring location required for triggeredsource water monitoring is E. coli-positive,the system has violated the E. coli MCL andmust also comply with 10 CSR 60-4.025(3)(A)3. If a system takes more thanone (1) repeat sample at the monitoring loca-tion required for triggered source water mon-itoring, the system may reduce the number ofadditional source water samples requiredunder 10 CSR 60-4.025(3)(A)3. by the num-ber of repeat samples taken at that locationthat were not E. coli-positive.

(II) If a system takes more than one(1) repeat sample at the monitoring locationrequired for triggered source water monitor-ing under 10 CSR 60-4.025(3)(A) and morethan one (1) repeat sample is E. coli-positive,the system has violated the E. coli MCL andmust also comply with 10 CSR 60-4.025(4)(A)1.

(III) If all repeat samples taken atthe monitoring location required for triggeredsource water monitoring are E. coli-negativeand a repeat sample taken at a monitoringlocation other than the one required for trig-gered source water monitoring is E. coli-pos-itive, the system has violated the E. coliMCL, but is not required to comply with 10CSR 60-4.025(3)(A)3.

6. The department may review, revise,and approve, as appropriate, repeat samplingproposed by systems under subparagraphs(3)(A)5.A.–B. of this rule. The system mustdemonstrate that the sample siting planremains representative of the water quality inthe distribution system. The department maydetermine that monitoring at the entry pointto the distribution system (especially forundisinfected ground water systems) is effec-tive to differentiate between potential sourcewater and distribution system problems.

(B) Special purpose samples. Special pur-

pose samples, such as those taken to deter-mine whether disinfection practices are suffi-cient following pipe placement, replacement,or repair, must not be used to determinewhether the coliform treatment techniquetrigger has been exceeded. Repeat samplestaken pursuant to section (8) of this rule arenot considered special purpose samples andmust be used to determine whether the col-iform treatment technique trigger has beenexceeded.

(C) Invalidation of total coliform samples.A total coliform-positive sample invalidatedunder this subsection (3)(C) does not counttoward meeting the minimum monitoringrequirements of this rule.

1. The department may invalidate a totalcoliform-positive sample only if any of thefollowing conditions are met:

A. The laboratory establishes thatimproper sample analysis caused the totalcoliform-positive result;

B. The department, on the basis of theresults of repeat samples collected as requiredunder subsection (8)(A) of this rule, deter-mines that the total coliform-positive sampleresulted from a domestic or other non-distri-bution system plumbing problem. Thedepartment cannot invalidate a sample on thebasis of repeat sample results unless all repeatsample(s) collected at the same tap as theoriginal total coliform-positive sample arealso total coliform-positive, and all repeatsamples collected at a location other than theoriginal tap are total coliform-negative (e.g.,the department cannot invalidate a total col-iform-positive sample on the basis of repeatsamples if all the repeat samples are total col-iform-negative, or if the system has only one(1) service connection).

C. The department has substantialgrounds to believe that a total coliform-posi-tive result is due to a circumstance or condi-tion that does not reflect water quality in thedistribution system. In this case, the systemmust still collect all repeat samples requiredunder subsection (8)(A) of this rule, and usethem to determine whether a coliform treat-ment technique trigger in section (9) of thisrule has been exceeded. To invalidate a totalcoliform-positive sample under this subsec-tion, the decision and supporting rationalemust be documented in writing, and approvedand signed by the supervisor of the depart-ment official who recommended the decision.The department must make this documentavailable to EPA and the public. The writtendocumentation must state the specific causeof the total coliform-positive sample and whataction the system has taken, or will take, tocorrect this problem. The department maynot invalidate a total coliform-positive sample

solely on the grounds that all repeat samplesare total coliform-negative.

2. A laboratory must invalidate a totalcoliform sample (unless total coliforms aredetected) if the sample produces a turbid cul-ture in the absence of gas production using ananalytical method where gas formation isexamined (e.g., the Multiple-TubeFermentation Technique), produces a turbidculture in the absence of an acid reaction inthe Presence-Absence (P-A) Coliform Test,or exhibits confluent growth or producescolonies too numerous to count with an ana-lytical method using a membrane filter (e.g.,Membrane Filter Technique). If a laboratoryinvalidates a sample because of such interfer-ence, the system must collect another samplefrom the same location as the original samplewithin twenty-four (24) hours of being noti-fied of the interference problem and have itanalyzed for the presence of total coliforms.The system must continue to re-sample with-in twenty-four (24) hours and have the sam-ples analyzed until it obtains a valid result.The department may waive the twenty-four(24) hour time limit on a case-by-case basis.Alternatively, the department may implementcriteria for waiving the twenty-four (24) hoursampling time limit to use in lieu of case-by-case extensions.

(4) Routine monitoring requirements for non-community water systems serving one thou-sand (1,000) or fewer people using onlyground water.

(A) General monitoring requirements. 1. The provisions of this section apply to

noncommunity water systems using onlyground water (except ground water under thedirect influence of surface water, as definedin 10 CSR 60-2.015) and serving one thou-sand (1,000) or fewer people.

2. Following any total coliform-positivesample taken under the provisions of this sec-tion, systems must comply with the repeatmonitoring requirements and E. coli analyti-cal requirements in section (8) of this rule.

3. Once all monitoring required by thissection and section (8) of this rule for a calen-dar month has been completed, systems mustdetermine whether any coliform treatmenttechnique triggers specified in section (9) ofthis rule have been exceeded. If any triggerhas been exceeded, systems must completeassessments as required by section (9) of thisrule.

4. For the purpose of determining eligi-bility for remaining on or qualifying for quar-terly monitoring under the provisions of para-graphs (4)(F)4. and (4)(G)2., respectively, ofthis rule for transient noncommunity watersystems, the department may elect to not



count monitoring violations under paragraph(10)(C)1. of this rule if the missed sample iscollected no later than the end of the moni-toring period following the monitoring periodin which the sample was missed. The systemmust collect the make-up sample in a differ-ent week than the routine sample for thatmonitoring period and should collect thesample as soon as possible during the moni-toring period. The department may not usethis provision under subsection (H) of thissection. This authority does not affect theprovisions of paragraph (10)(C)1. of this ruleand 10 CSR 60-7.010(11)(D).

(B) Monitoring frequency for total col-iforms. Unless the department approves of alesser frequency in writing and the systemmeets criteria provided under subsections(4)(C) through (4)(H) and (4)(J) of this rule,the minimum monitoring frequency for totalcoliforms is one (1) sample per month exceptthat systems practicing iron removal or limesoftening must collect at least five (5) routinesamples per month. In addition, the depart-ment may require a greater frequency if nec-essary. Seasonal systems must meet the mon-itoring requirements of subsection (4)(I) ofthis rule.

(C) Transition to the Revised Total ColiformRule. The department will perform a specialmonitoring evaluation during each sanitarysurvey to review the status of the system,including the distribution system, to determinewhether the system is on an appropriate mon-itoring schedule. After the department hasperformed the special monitoring evaluationduring each sanitary survey, the departmentmay modify the system’s monitoring schedule,as necessary, or it may allow the system to stayon its existing monitoring schedule, consistentwith the provisions of this section (4). Thedepartment may not allow systems to beginless frequent monitoring under the specialmonitoring evaluation unless the system hasalready met the applicable criteria for less fre-quent monitoring in this section. For seasonalsystems on quarterly or annual monitoring,this evaluation must include review of theapproved sample siting plan, which must des-ignate the time period(s) for monitoring basedon site-specific considerations (e.g., duringperiods of highest demand or highest vulnera-bility to contamination). The seasonal systemmust collect compliance samples during thesetime periods.

(D) Annual site visits. Systems on annualmonitoring, including seasonal systems, musthave an initial and recurring annual site visitby the department that is equivalent to a Level2 assessment or an annual voluntary Level 2assessment that meets the criteria in subsec-tion (9)(B) to remain on annual monitoring.

The periodic required sanitary survey may beused to meet the requirement for an annualsite visit for the year in which the sanitarysurvey was completed.

(E) Criteria for annual monitoring. Thedepartment may reduce the monitoring fre-quency for a well-operated ground water sys-tem from quarterly routine monitoring to noless than annual monitoring, if the systemdemonstrates that it meets the criteria forreduced monitoring in paragraphs (4)(E)1.-3.of this rule, except for a system that has beenon increased monitoring under the provisionsof subsection (4)(F) of this rule. A system onincreased monitoring under subsection (4)(F)of this rule must meet the provisions of sub-section (4)(G) of this rule to go to quarterlymonitoring and must meet the provisions ofsubsection (4)(H) of this rule to go to annualmonitoring.

1. The system has a clean compliancehistory for a minimum of twelve (12) months.

2. The most recent sanitary surveyshows that the system is free of sanitarydefects or has corrected all identified sanitarydefects, has a protected water source, andmeets approved construction standards.

3. The department has conducted anannual site visit within the last twelve (12)months, and the system has corrected allidentified sanitary defects. The system maysubstitute a Level 2 assessment that meets thecriteria in subsection (9)(B) of this rule forthe department annual site visit.

(F) Increased Monitoring Requirements forsystems on quarterly or annual monitoring. Asystem on quarterly or annual monitoring thatexperiences any of the events identified inparagraphs (4)(F)1.–4. of this section mustbegin monthly monitoring the month follow-ing the event. A system on annual monitoringthat experiences the event identified in para-graph (4)(F)5. of this rule must begin quar-terly monitoring the quarter following theevent. The system must continue monthly orquarterly monitoring until the requirementsin subsection (4)(G) of this rule for quarterlymonitoring or subsection (4)(H) of this rulefor annual monitoring are met. A system onmonthly monitoring for reasons other thanthose identified in paragraphs (4)(F)1.–4. ofthis rule is not considered to be on increasedmonitoring for the purposes of subsections(4)(G) and (4)(H) of this section.

1. The system triggers a Level 2 assess-ment or two (2) Level 1 assessments underthe provisions of section (9) in a rollingtwelve (12) month period.

2. The system has an E. coli MCL vio-lation.

3. The system has a coliform treatmenttechnique violation.

4. The system has two (2) Revised TotalColiform Rule monitoring violations or one(1) Revised Total Coliform Rule monitoringviolation and one (1) Level 1 assessmentunder the provisions of section (9) in a rollingtwelve (12) month period for a system onquarterly monitoring.

5. The system has one (1) Revised TotalColiform Rule monitoring violation for a sys-tem on annual monitoring.

(G) Requirements for returning to quarter-ly monitoring. The department may reducethe monitoring frequency for a system onmonthly monitoring triggered under subsec-tion (4)(F) of this section to quarterly moni-toring if the system meets the criteria in para-graphs (4)(G)1. and 2. of this rule.

1. Within the last twelve (12) months,the system must have a completed sanitarysurvey or a site visit by the department or avoluntary Level 2 assessment by a partyapproved by the department, be free of sani-tary defects, and have a protected watersource; and

2. The system must have a clean com-pliance history for a minimum of twelve (12)months.

(H) Requirements for systems on increasedmonitoring to qualify for annual monitoring.The department may reduce the monitoringfrequency for a system on increased monitor-ing under subsection (4)(F) of this section ifthe system meets the criteria in subsection(4)(G) of this section plus the criteria in para-graphs (4)(H)1. and 2. of this section.

1. An annual site visit by the departmentand correction of all identified sanitarydefects. The system may substitute a volun-tary Level 2 assessment by a party approvedby the department for the department annualsite visit in any given year.

2. The system must have in place oradopt one (1) or more additional enhance-ments to the water system barriers to contam-ination in subparagraphs (4)(H)2.A.–E. ofthis section.

A. Cross connection control, asapproved by the department.

B. An operator certified by an appro-priate department certification program orregular visits by a circuit rider certified by anappropriate department certification pro-gram.

C. Continuous disinfection enteringthe distribution system and a residual in thedistribution system in accordance with crite-ria specified by the department.

D. Demonstration of maintenance ofat least a 4-log removal or inactivation ofviruses as provided for under 10 CSR 60-4.025(4)(B)3.

E. Other equivalent enhancements to


Secretary of State


water system barriers as approved by thedepartment.

(I) Seasonal systems. 1. All seasonal systems must demonstrate

completion of a department-approved start-upprocedure, which may include a requirementfor startup sampling prior to serving water tothe public.

2. A seasonal system must monitor everymonth that it is in operation unless it meets thecriteria in subparagraphs (4)(I)2.A.–C. of thisrule to be eligible for monitoring less fre-quently than monthly, except as providedunder subsection (4)(C) of this rule.

A. Seasonal systems monitoring lessfrequently than monthly must have anapproved sample siting plan that designatesthe time period for monitoring based on site-specific considerations (e.g., during periodsof highest demand or highest vulnerability tocontamination). Seasonal systems must col-lect compliance samples during this timeperiod.

B. To be eligible for quarterly moni-toring, the system must meet the criteria insubsection (4)(G) of this section.

C. To be eligible for annual monitor-ing, the system must meet the criteria undersubsection (4)(H) of this rule.

3. The department may exempt any sea-sonal system from some or all of the require-ments for seasonal systems if the entire dis-tribution system remains pressurized duringthe entire period that the system is not oper-ating, except that systems that monitor lessfrequently than monthly must still monitorduring the vulnerable period designated bythe department.

(J) Additional routine monitoring themonth following a total coliform-positivesample. Systems collecting samples on aquarterly or annual frequency must conductadditional routine monitoring the month fol-lowing one (1) or more total coliform-posi-tive samples (with or without a Level 1 treat-ment technique trigger). Systems must collectat least three (3) routine samples during thenext month, except that the department maywaive this requirement if the conditions ofparagraphs (4)(J)1.–3. of this rule are met.Systems may either collect samples at regulartime intervals throughout the month or maycollect all required routine samples on a sin-gle day if samples are taken from differentsites. Systems must use the results of addi-tional routine samples in coliform treatmenttechnique trigger calculations under subsec-tion (9)(A) of this rule.

1. The department may waive therequirement to collect three (3) routine sam-ples the next month in which the system pro-vides water to the public if the department, or

an agent approved by the department, per-forms a site visit before the end of the nextmonth in which the system provides water tothe public. Although a sanitary survey neednot be performed, the site visit must be suf-ficiently detailed to allow the department todetermine whether additional monitoringand/or any corrective action is needed. Thedepartment cannot approve an employee ofthe system to perform this site visit, even ifthe employee is an agent approved by thedepartment to perform sanitary surveys.

2. The department may waive therequirement to collect three (3) routine sam-ples the next month in which the system pro-vides water to the public if the departmenthas determined why the sample was total col-iform-positive and has established that thesystem has corrected the problem or will cor-rect the problem before the end of the nextmonth in which the system serves water to thepublic. In this case, the department must doc-ument this decision to waive the followingmonth’s additional monitoring requirement inwriting, have it approved and signed by thesupervisor of the department official whorecommends such a decision, and make thisdocument available to the EPA and public.The written documentation must describe thespecific cause of the total coliform-positivesample and what action the system has takenand/or will take to correct this problem.

3. The department may not waive therequirement to collect three (3) additionalroutine samples the next month in which thesystem provides water to the public solely onthe grounds that all repeat samples are totalcoliform-negative. If the department deter-mines that the system has corrected the con-tamination problem before the system takesthe set of repeat samples required in section(8) of this rule, and all repeat samples weretotal coliform-negative, the department maywaive the requirement for additional routinemonitoring the next month.

(5) Routine monitoring requirements for com-munity water systems serving one thousand(1,000) or fewer people using only groundwater.

(A) General Routine Monitoring. 1. The provisions of this section apply to

community water systems using only groundwater (except ground water under the directinfluence of surface water, as defined in 10CSR 60-2.015) and serving one thousand(1,000) or fewer people.


3. Once all monitoring required by sec-tion (5) and section (8) of this rule for a cal-endar month has been completed, systemsmust determine whether any coliform treat-ment technique triggers specified in section(9) of this rule have been exceeded. If anytrigger has been exceeded, systems mustcomplete assessments as required by section(9) of this rule.

(B) Monitoring frequency for total col-iforms. Unless the department approves of alesser frequency in writing as provided forunder subsections (5)(C)-(F) of this rule, themonitoring frequency for total coliform is one(1) sample per month except that systemspracticing iron removal or lime softeningmust collect at least five (5) routine samplesper month.

(C) Transition to the Revised TotalColiform Rule.

1. Unless any of the conditions in sub-section (5)(E) of this rule are triggered, orunless otherwise directed by the department,all systems must continue to monitor accord-ing to the total coliform monitoring sched-ules under the Environmental ProtectionAgency’s Code of Federal Regulations, 40CFR 141.21, published February 13, 2013.This document is incorporated by referencewithout any later amendments or modifica-tions. To obtain a copy, contact the U.S.Government Printing Office at 732 NorthCapitol Street NW, Washington, D.C.,20401, toll free at (866) 512-1800 or by vis-iting https://bookstore.gpo.gov.

2. The department must perform a spe-cial monitoring evaluation during each sani-tary survey to review the status of the system,including the distribution system, to deter-mine whether the system is on an appropriatemonitoring schedule. After the departmenthas performed the special monitoring evalua-tion during each sanitary survey, the depart-ment may modify the system’s monitoringschedule, as necessary, or it may allow thesystem to stay on its existing monitoringschedule, consistent with the provisions ofthis section. The department may not allowsystems to begin less frequent monitoringunder the special monitoring evaluationunless the system has already met the appli-cable criteria for less frequent monitoring inthis section.

(D) Criteria for reduced monitoring. 1. The department may reduce the mon-

itoring frequency from monthly monitoring tono less than quarterly monitoring if the sys-tem is in compliance with department-certi-fied operator provisions and demonstratesthat it meets the criteria in subparagraphs(5)(D)1.A.–C. of this rule. A system thatloses its certified operator must return to



monthly monitoring the month following thatloss.

A. The system has a clean compliancehistory for a minimum of twelve (12) months.

B. The most recent sanitary surveyshows the system is free of sanitary defects(or has an approved plan and schedule to cor-rect them and is in compliance with the planand the schedule), has a protected watersource and meets approved construction stan-dards.

C. The system meets at least one (1)of the following criteria:

(I) The system had an annual sitevisit by the department that is equivalent to aLevel 2 assessment or an annual Level 2assessment by a party approved by the depart-ment and correction of all identified sanitarydefects (or the system has an approved planand schedule to correct them and is in com-pliance with the plan and schedule);

(II) The system has cross connec-tion control, as approved by the department;

(III) The system has continuousdisinfection entering the distribution systemand a residual in the distribution system inaccordance with criteria specified by thedepartment;

(IV) The system has a demonstra-tion of maintenance of at least a 4-logremoval or inactivation of viruses as providedfor under 10 CSR 60-4.025(4)(B)3.; or

(V) Other equivalent enhancementsto water system barriers as approved by thedepartment.

(E) Return to routine monthly monitoringrequirements. Systems on quarterly monitor-ing that experience any of the events in para-graphs (5)(E)1.-4. of this rule must beginmonthly monitoring the month following theevent. The system must continue monthlymonitoring until it meets the reduced moni-toring requirements in subsection (5)(D) ofthis rule.

1. The system triggers a Level 2 assess-ment or two (2) Level 1 assessments in arolling twelve (12) month period.

2. The system has an E. coli MCL vio-lation.

3. The system has a coliform treatmenttechnique violation.

4. The system has two (2) Revised TotalColiform Rule monitoring violations in arolling twelve (12) month period.

(F) Additional routine monitoring themonth following a total coliform-positivesample. Systems collecting samples on aquarterly frequency must conduct additionalroutine monitoring the month following one(1) or more total coliform-positive samples(with or without a Level 1 treatment tech-nique trigger). Systems must collect at least

three (3) routine samples during the nextmonth, except that the department may waivethis requirement if the conditions of para-graphs (5)(F)1., 2., or 3. of this rule are met.Systems may either collect samples at regulartime intervals throughout the month or maycollect all required routine samples on a sin-gle day if samples are taken from differentsites. Systems must use the results of addi-tional routine samples in coliform treatmenttechnique trigger calculations.

1. The department may waive therequirement to collect three (3) routine sam-ples the next month in which the system pro-vides water to the public if the department, oran agent approved by the department, per-forms a site visit before the end of the nextmonth in which the system provides water tothe public. Although a sanitary survey neednot be performed, the site visit must be suf-ficiently detailed to allow the department todetermine whether additional monitoring orany corrective action, or both, is needed. Thedepartment cannot approve an employee ofthe system to perform this site visit, even ifthe employee is an agent approved by thedepartment to perform sanitary surveys.

2. The department may waive therequirement to collect three (3) routine sam-ples the next month in which the system pro-vides water to the public if the departmenthas determined why the sample was total col-iform-positive and has established that thesystem has corrected the problem or will cor-rect the problem before the end of the nextmonth in which the system serves water to thepublic. In this case, the department must doc-ument this decision to waive the followingmonth’s additional monitoring requirement inwriting, have it approved and signed by thesupervisor of the department official whorecommends such a decision, and make thisdocument available to the U.S. EPA and thepublic. The written documentation mustdescribe the specific cause of the total col-iform-positive sample and what action thesystem has taken and/or will take to correctthis problem.

3. The department may not waive therequirement to collect three (3) additionalroutine samples the next month in which thesystem provides water to the public solely onthe grounds that all repeat samples are totalcoliform-negative. If the department deter-mines that the system has corrected the con-tamination problem before the system takesthe set of repeat samples required in section(8) of this rule, and all repeat samples weretotal coliform-negative, the department maywaive the requirement for additional routinemonitoring the next month.

(6) Routine monitoring requirements for sur-face water and ground water under the directinfluence of surface water public water sys-tems serving one thousand (1,000) or fewerpeople.

(A) General Routine Monitoring. 1. This section (6) applies to surface

water and ground water under the directinfluence of surface water systems servingone thousand (1,000) or fewer people.

2. Following any total coliform-positivesample taken under the provisions of this sec-tion (6), systems must comply with the repeatmonitoring requirements and E. coli analyti-cal requirements in section (8) of this rule.

3. Once all monitoring required by thissection (6) and section (8) of this rule for acalendar month has been completed, systemsmust determine whether any coliform treat-ment technique triggers specified in section(9) have been exceeded. If any trigger hasbeen exceeded, systems must completeassessments as required by section (9) of thisrule.

4. Seasonal systems.A. All seasonal systems must demon-

strate completion of a department-approvedstart-up procedure, which may include arequirement for start-up sampling prior toserving water to the public.

B. The department may exempt anyseasonal system from some or all of therequirements for seasonal systems if theentire distribution system remains pressurizedduring the entire period that the system is notoperating.

(B) Routine monitoring frequency for totalcoliforms. Surface water and groundwaterunder the direct influence of surface watersystems (including consecutive systems) mustmonitor monthly. Systems may not reducemonitoring. Primary public water systemsmust collect a minimum of five (5) routinesamples per month. In addition, the depart-ment may require a greater frequency if nec-essary.

(7) Routine monitoring requirements for pub-lic water systems serving more than one thou-sand (1,000) people.

(A) General Routine Monitoring. 1. The provisions of this section apply to

public water systems serving more than onethousand (1,000) people.


3. Once all monitoring required by thissection and section (8) of this rule for a cal-endar month has been completed, systems


Secretary of State


must determine whether any coliform treat-ment technique triggers specified in section(9) of this rule have been exceeded. If anytrigger has been exceeded, systems mustcomplete assessments as required by section(9) of this rule.

4. Seasonal systems. A. All seasonal systems must demon-

strate completion of a department-approvedstart-up procedure, which may include arequirement for start-up sampling prior toserving water to the public.

B. The department may exempt anyseasonal system from some or all of therequirements for seasonal systems if theentire distribution system remains pressurizedduring the entire period that the system is notoperating.

(B) Monitoring frequency for total col-iforms. The monitoring frequency for totalcoliforms is based on the population servedby the system, as follows, except for systemsusing surface water or groundwater under thedirect influence of surface water or practicingiron removal or lime softening must collect aminimum of five (5) routine samples permonth:



(C) Reduced monitoring. Systems may notreduce monitoring, except for noncommunitywater systems using only ground water (andnot ground water under the direct influence ofsurface water) serving one thousand (1,000)or fewer people in some months and morethan one thousand (1,000) people in othermonths. In months when more than one thou-sand (1,000) people are served, the systemsmust monitor at the frequency specified insubsection (7)(B) of this rule. In monthswhen one thousand (1,000) or fewer peopleare served, the department may reduce themonitoring frequency, in writing, to a fre-quency allowed under section (4) of this rule

for a similarly situated system that alwaysserves one thousand (1,000) or fewer people,taking into account the provisions in subsec-tion (4)(E)–(G) of this rule.

(8) Repeat monitoring and E. coli require-ments.

(A) Repeat monitoring. 1. If a sample taken under sections (4)–

(7) of this rule is total coliform-positive, thesystem must collect a set of repeat sampleswithin twenty-four (24) hours of being noti-fied of the positive result. The system mustcollect no fewer than three (3) repeat samplesfor each total coliform-positive sample found.

The department may extend the twenty-four(24) hour limit on a case-by-case basis if thesystem has a logistical problem in collectingthe repeat samples within twenty-four (24)hours that is beyond its control. Alternatively,the department may implement criteria forthe system to use in lieu of case-by-caseextensions. In the case of an extension, thedepartment must specify how much time thesystem has to collect the repeat samples. Thedepartment cannot waive the requirement fora system to collect repeat samples in para-graphs (8)(A)1.-3. of this rule.

2. The system must collect all repeatsamples on the same day, except that the


Secretary of State


Total Coliform Monitoring Frequency for Public Water Systems Serving More Than 1,000 People ------------------------------------------------------------------------ Minimum number of Population served samples per month ------------------------------------------------------------------------ 1,001 to 2,500....................................... 2 2,501 to 3,300....................................... 3 3,301 to 4,100....................................... 4 4,101 to 4,900....................................... 5 4,901 to 5,800....................................... 6 5,801 to 6,700....................................... 7 6,701 to 7,600....................................... 8 7,601 to 8,500....................................... 9 8,501 to 12,900...................................... 10 12,901 to 17,200..................................... 15 17,201 to 21,500..................................... 20 21,501 to 25,000..................................... 25 25,001 to 33,000..................................... 30 33,001 to 41,000..................................... 40 41,001 to 50,000..................................... 50 50,001 to 59,000..................................... 60 59,001 to 70,000..................................... 70 70,001 to 83,000..................................... 80 83,001 to 96,000..................................... 90 96,001 to 130,000.................................... 100 130,001 to 220,000................................... 120 220,001 to 320,000................................... 150 320,001 to 450,000................................... 180 450,001 to 600,000................................... 210 600,001 to 780,000................................... 240 780,001 to 970,000................................... 270 970,001 to 1,230,000................................. 300 1,230,001 to 1,520,000............................... 330 1,520,001 to 1,850,000............................... 360 1,850,001 to 2,270,000............................... 390 2,270,001 to 3,020,000............................... 420 3,020,001 to 3,960,000............................... 450 3,960,001 or more.................................... 480 ------------------------------------------------------------------------

department may allow a system with a singleservice connection to collect the required setof repeat samples over a three (3) day periodor to collect a larger volume repeat sample(s)in one (1) or more sample containers of anysize, as long as the total volume collected isat least three hundred milliliters (300 mL).Systems with more than one (1) service con-nection, but fewer service connections thanthe required number of repeat samples, shallcollect repeat samples as directed by thedepartment.

3. The system must collect an addition-al set of repeat samples in the manner speci-fied in paragraphs (8)(A)1.-3. of this rule ifone (1) or more repeat samples in the currentset of repeat samples is total coliform-posi-tive. The system must collect the additionalset of repeat samples within twenty-four (24)hours of being notified of the positive result,unless the department extends the limit asprovided in paragraph (8)(A)1. of this rule.The system must continue to collect addition-al sets of repeat samples until either total col-iforms are not detected in one (1) completeset of repeat samples or the system deter-mines that a coliform treatment techniquetrigger specified in subsection (9)(A) of thisrule has been exceeded as a result of a repeatsample being total coliform-positive and noti-fies the department. If a trigger identified insection (9) of this rule is exceeded as a resultof a routine sample being total coliform-pos-itive, systems are required to conduct onlyone (1) round of repeat monitoring for eachtotal coliform-positive routine sample.

4. After a system collects a routine sam-ple and before it learns the results of the anal-ysis of that sample, if it collects another rou-tine sample(s) from within five (5) adjacentservice connections of the initial sample, andthe initial sample, after analysis, is found tocontain total coliforms, then the system maycount the subsequent sample(s) as a repeatsample instead of as a routine sample.

5. Results of all routine and repeat sam-ples taken under sections (4)-(8) of this rulenot invalidated by the department must beused to determine whether a coliform treat-ment technique trigger specified in section(9) of this rule has been exceeded.

(B) Escherichia coli (E. coli) testing. 1. If any routine or repeat sample is total

coliform-positive, the system must analyzethat total coliform-positive culture medium todetermine if E. coli are present. If E. coli arepresent, the system must notify the depart-ment by the end of the day when the systemis notified of the test result, unless the systemis notified of the result after the departmentoffice is closed and the department does nothave either an after-hours phone line or an

alternative notification procedure, in whichcase the system must notify the departmentbefore the end of the next business day.

2. The department has the discretion toallow a system, on a case-by-case basis, toforgo E. coli testing on a total coliform-pos-itive sample if that system assumes that thetotal coliform-positive sample is E. coli-pos-itive. Accordingly, the system must notifythe department as specified in paragraph(8)(B)1. of this rule and the provisions of theEnvironmental Protection Agency’s Code ofFederal Regulations, 40 CFR 141.63(c),published February 13, 2013. This docu-ment is incorporated by reference withoutany later amendments or modifications. Toobtain a copy, contact the U.S. GovernmentPrinting Office at 732 North Capitol StreetNW, Washington, D.C., 20401, toll free at(866) 512-1800 or by visiting https://book-store.gpo.gov.

(9) Coliform treatment technique triggers andassessment requirements for protectionagainst potential fecal contamination.

(A) Treatment technique triggers. Systemsmust conduct assessments in accordance withsubsection (9)(B) of this rule after exceedingtreatment technique triggers in paragraphs(9)(A)1. and (9)(A)2. of this rule.

1. Level 1 treatment technique triggers.A. For systems taking forty (40) or

more samples per month, the system exceedsfive percent (5.0%) total coliform-positivesamples for the month.

B. For systems taking fewer than forty(40) samples per month, the system has two(2) or more total coliform-positive samples inthe same month.

C. The system fails to take everyrequired repeat sample after any single totalcoliform-positive sample.

2. Level 2 treatment technique triggers.A. An E. coli MCL violation, as

specified in section (10) of this rule. B. A second Level 1 trigger as defined

in paragraph (9)(A)1. of this rule, within arolling twelve (12) month period, unless thedepartment has determined a likely reasonthat the samples that caused the first Level 1treatment technique trigger were total col-iform-positive and has established that thesystem has corrected the problem.

C. For systems with approved annualmonitoring, a Level 1 trigger in two (2) con-secutive years.

(B) Requirements for assessments. 1. Systems must ensure that Level 1 and

2 assessments are conducted in order to iden-tify the possible presence of sanitary defectsand defects in distribution system coliformmonitoring practices. Level 2 assessments

must be conducted by parties approved by thedepartment.

2. When conducting assessments, sys-tems must ensure that the person performingthe assessment evaluates minimum elementsthat include review and identification of inad-equacies in sample sites; sampling protocol;sample processing; atypical events that couldaffect distributed water quality or indicatethat distributed water quality was impaired;changes in distribution system maintenanceand operation that could affect distributedwater quality (including water storage);source and treatment considerations that bearon distributed water quality, where appropri-ate (e.g., small ground water systems); andexisting water quality monitoring data. Thesystem must conduct the assessment consis-tent with any department directives that tailorspecific assessment elements with respect tothe size and type of the system and the size,type, and characteristics of the distributionsystem.

3. Level 1 Assessments. A system mustconduct a Level 1 assessment consistent withdepartment requirements if the systemexceeds one (1) of the treatment techniquetriggers in paragraph (9)(A)1. of this rule.The Level 1 assessment must be conductedconsistent with any department directives thattailor specific assessment elements withrespect to the size and type of the system andthe size, type, and characteristics of the dis-tribution system.

A. The system must complete a Level1 assessment as soon as practical after anytrigger in paragraph (9)(A)1. of this rule. Inthe completed assessment form, the systemmust describe sanitary defects detected, cor-rective actions completed, and a proposedtimetable for any corrective actions notalready completed. The assessment form mayalso note that no sanitary defects were identi-fied. The system must submit the completedLevel 1 assessment form to the departmentwithin thirty (30) days after the system learnsthat it has exceeded a trigger.

B. If the department reviews the com-pleted Level 1 assessment and determinesthat the assessment is not sufficient (includ-ing any proposed timetable for any correctiveactions not already completed), the depart-ment must consult with the system. If thedepartment requires revisions after consulta-tion, the system must submit a revised assess-ment form to the department on an agreed-upon schedule not to exceed thirty (30) daysfrom the date of the consultation.

C. Upon completion and submissionof the assessment form by the system, thedepartment must determine if the system hasidentified a likely cause for the Level 1 trigger



and, if so, establish that the system has cor-rected the problem, or has included a sched-ule acceptable to the department for correct-ing the problem.

4. Level 2 Assessments. A system mustensure that a Level 2 assessment consistentwith department requirements is conducted ifthe system exceeds one (1) of the treatmenttechnique triggers in paragraph (9)(A)2. ofthis rule. The Level 2 assessment must beconducted consistent with any departmentdirectives that tailor specific assessment ele-ments with respect to the size and type of thesystem and the size, type, and characteristicsof the distribution system. The system mustcomply with any expedited actions or addi-tional actions required by the department inthe case of an E. coli MCL violation.

A. The system must ensure that aLevel 2 assessment is completed by thedepartment or by a party approved by thedepartment as soon as practical after any trig-ger in paragraph (9)(A)2. of this rule. Thesystem must submit a completed Level 2assessment form to the department withinthirty (30) days after the system learns that ithas exceeded a trigger. The assessment formmust describe sanitary defects detected, cor-rective actions completed, and a proposedtimetable for any corrective actions notalready completed. The assessment form mayalso note that no sanitary defects were identi-fied.

B. The system may conduct Level 2assessments if the system has staff or man-agement with the certification or qualifica-tions specified by the department unless oth-erwise directed by the department.

C. If the department reviews the com-pleted Level 2 assessment and determinesthat the assessment is not sufficient (includ-ing any proposed timetable for any correctiveactions not already completed), the depart-ment must consult with the system. If thedepartment requires revisions after consulta-tion, the system must submit a revised assess-ment form to the department on an agreed-upon schedule not to exceed thirty (30) days.

D. Upon completion and submissionof the assessment form by the system, thedepartment must determine if the system hasidentified a likely cause for the Level 2 trig-ger and determine whether the system hascorrected the problem, or has included aschedule acceptable to the department forcorrecting the problem.

(C) Corrective Action. Systems must cor-rect sanitary defects found through eitherLevel 1 or 2 assessments conducted undersubsection (9)(B) of this rule. For correctionsnot completed by the time of submission ofthe assessment form, the system must com-

plete the corrective action(s) in compliancewith a timetable approved by the departmentin consultation with the system. The systemmust notify the department when each sched-uled corrective action is completed.

(D) Consultation. At any time during theassessment or corrective action phase, eitherthe water system or the department mayrequest a consultation with the other party todetermine the appropriate actions to be taken.The system may consult with the departmenton all relevant information that may impacton its ability to comply with a requirement ofthis rule, including the method of accom-plishment, an appropriate timeframe, andother relevant information.

(10) Violations.(A) E. coli Maximum Contaminant Level

(MCL) Violation. A system is in violation ofthe MCL for E. coli when any of the condi-tions identified in paragraphs (10)(A)1.-4. ofthis rule occur. For purposes of the publicnotification requirements in 10 CSR 60-8.010, violation of the MCL for E. coli maypose an acute risk to health.

1. The system has an E. coli-positiverepeat sample following a total coliform-pos-itive routine sample.

2. The system has a total coliform-posi-tive repeat sample following an E. coli-posi-tive routine sample.

3. The system fails to take all requiredrepeat samples following an E. coli-positiveroutine sample.

4. The system fails to test for E. coliwhen any repeat sample tests positive fortotal coliform.

(B) Treatment technique violation. 1. A treatment technique violation

occurs when a system exceeds a treatmenttechnique trigger specified in subsection(9)(A) of this rule and then fails to conductthe required assessment or corrective actionswithin the timeframe specified in subsections(9)(B) and (9)(C) of this rule.

2. A treatment technique violationoccurs when a seasonal system fails to com-plete a department-approved start-up proce-dure prior to serving water to the public.

(C) Monitoring violations. 1. Failure to take every required routine

or additional routine sample in a complianceperiod is a monitoring violation.

2. Failure to analyze for E. coli follow-ing a total coliform-positive routine sample isa monitoring violation.

(D) Reporting violations. 1. Failure to submit a monitoring report

or completed assessment form after a systemproperly conducts monitoring or assessmentin a timely manner is a reporting violation.

2. Failure to notify the department fol-lowing an E. coli-positive sample as requiredby paragraph (8)(B)1. of this rule in a timelymanner is a reporting violation.

3. Failure to submit certification of com-pletion of department-approved start-up pro-cedure by a seasonal system is a reportingviolation.

(11) Reporting Requirements. Reportingrequirements are in section (11) of 10 CSR60-7.010 Reporting Requirements.

(12) Record-Keeping Requirements.Recordkeeping requirements are in section(5) of 10 CSR 60-9.010 Requirements forMaintaining Public Water System Records.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed Aug. 12, 2015, effectiveMarch 30, 2016. Amended: Filed June 13,2018, effective Feb. 28, 2019.

*Original authority: 640.100, RSMo 1939, amended 1978,1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996, 1998,1999, 2002, 2006, 2012, 2014.

10 CSR 60-4.025 Ground Water RuleMonitoring and Treatment TechniqueRequirements

PURPOSE: This rule sets standards for pub-lic water systems using ground water, includ-ing requirements for monitoring, treatmenttechniques, and corrective actions where sig-nificant deficiencies are found. The rule isbased on the requirements in the federalGround Water Rule found in subpart S of 40CFR part 141, July 1, 2008.

PUBLISHER’S NOTE: The secretary of statehas determined that the publication of theentire text of the material which is incorpo-rated by reference as a portion of this rulewould be unduly cumbersome or expen-sive. This material as incorporated by refer-ence in this rule shall be maintained by theagency at its headquarters and shall be madeavailable to the public for inspection andcopying at no more than the actual cost ofreproduction. This note applies only to thereference material. The entire text of the ruleis printed here.

(1) General Requirements and Applicability.(A) Scope of this rule. The requirements of

this rule constitute National PrimaryDrinking Water Regulations.

(B) Applicability. This rule applies to allpublic water systems that use ground waterexcept that it does not apply to public watersystems that combine all of their ground


Secretary of State


water with surface water or with groundwater under the direct influence of surfacewater prior to treatment. Also, it does notapply to ground water systems under thedirect influence of surface water. For the pur-poses of this rule, ground water system isdefined as any public water system meetingthis applicability statement, including consec-utive systems receiving finished groundwater.

(C) General Requirements. 1. Systems subject to this rule must

comply with sanitary survey informationrequirements described in section (2) of thisrule.

2. Wherever it is used in this rule, theterm “4-log treatment of viruses” shall meantreatment to at least ninety-nine and ninety-nine hundredths percent (99.99%) (4-log)treatment of viruses using inactivation,removal, or a department-approved combina-tion of 4-log virus inactivation and removalbefore or at the first customer.

3. For the purposes of this rule, signifi-cant deficiencies include, but are not limitedto, defects in design, operation, or mainte-nance, or a failure or malfunction of thesources, treatment, storage, or distributionsystem that the department determines arecausing, or have the potential for causing, theintroduction of contamination into the waterdelivered to consumers.

4. Systems subject to this rule mustcomply with microbial source water monitor-ing requirements for ground water systemsthat do not treat all of their ground water toat least ninety-nine and ninety-nine hun-dredths percent (99.99%) (4-log) treatment ofviruses before or at the first customer asdescribed in section (3) of this rule.

5. Systems subject to this rule mustcomply with treatment technique require-ments, described in section (4) of this rulethat apply to ground water systems that havefecally contaminated source waters, as deter-mined by source water monitoring conductedunder section (3) of this rule, or that have sig-nificant deficiencies that are identified by thedepartment, or that are identified by the U.S.Environmental Protection Agency under sec-tion 1445 of the Safe Drinking Water Act. Aground water system with fecally contaminat-ed source water or with significant deficien-cies subject to the treatment techniquerequirements of this rule must implement one(1) or more of the following corrective actionoptions under the direction and approval ofthe department:

A. Correct all significant deficien-cies;

B. Provide an alternate source ofwater;

C. Eliminate the source of contamina-tion; or

D. Provide treatment that reliablyachieves at least 4-log treatment of virusesbefore or at the first customer.

6. Ground water systems that arerequired by this rule to provide at least 4-logtreatment of viruses before or at the first cus-tomer are required to conduct compliancemonitoring to demonstrate treatment effec-tiveness, as described in subsection (4)(B) ofthis rule.

7. If requested by the department,ground water systems must provide any exist-ing information that will enable the depart-ment to perform a hydrogeologic sensitivityassessment. For the purposes of this rule, ahydrogeologic sensitivity assessment is adetermination of whether ground water sys-tems obtain water from hydrogeologicallysensitive settings.

(2) Sanitary Surveys and Inspections forGround Water Systems.

(A) Ground water systems must provide, atthe department’s request, any existing infor-mation that will enable the department toconduct a sanitary survey or inspection.

(B) For the purposes of this rule, a sanitarysurvey includes, but is not limited to, anonsite review, under the supervision of anengineer, of the water source(s) (identifyingsources of contamination by using results ofsource water assessments or other relevantinformation where available), facilities,equipment, operation, maintenance, andmonitoring compliance of a public water sys-tem in order to evaluate the adequacy of thesystem, its sources and operations, and thedistribution of safe drinking water.

(C) The sanitary survey or inspection mustinclude an evaluation of the water system’s—

1. Source;2. Treatment; 3. Distribution system; 4. Finished water storage; 5. Pumps, pump facilities, and controls; 6. Monitoring, reporting, and data veri-

fication; 7. System management and operation;

and 8. Operator compliance with department

requirements.

(3) Ground Water Source MicrobialMonitoring.

(A) Triggered Source Water Monitoring.1. General requirements. A ground

water system must conduct triggered sourcewater monitoring if the following conditionsexist:

A. The system does not provide at

least 4-log treatment of viruses (using inacti-vation, removal, or a state-approved combi-nation of 4-log virus inactivation andremoval) before or at the first customer foreach ground water source; and

B. The system is notified that a sam-ple collected under 10 CSR 60-4.022(4)-(7) istotal coliform-positive and the sample is notinvalidated under 10 CSR 60-4.022(3)(C).

2. Sampling requirements. A groundwater system must collect, within twenty-four(24) hours of notification of the total col-iform-positive sample, at least one (1) groundwater source sample from each ground watersource in use at the time the total coliform-positive sample was collected under 10 CSR60-4.022(4)-(7) except as provided in sub-paragraph (3)(A)2.B. of this rule.

A. The department may extend thetwenty-four (24) hour time limit on a case-by-case basis if the system cannot collect theground water source water sample withintwenty-four (24) hours due to circumstancesbeyond its control. In the case of an exten-sion, the department will specify how muchtime the system has to collect the sample.

B. If approved by the department, sys-tems with more than one (1) ground watersource may meet the requirements of this sub-paragraph by sampling a representativeground water source or sources. If directedby the department, systems must submit fordepartment approval a triggered source watermonitoring plan that identifies one (1) ormore ground water sources that are represen-tative of each monitoring site in the system’ssample siting plan under 10 CSR 60-4.022(3)and that the system intends to use for repre-sentative sampling for triggered source watermonitoring.

C. A ground water system servingone thousand (1,000) or fewer people mayuse a repeat sample collected from a groundwater source to meet both the requirements of10 CSR 60-4.022 and to satisfy the monitor-ing requirements of paragraph (3)(A)2. ofthis rule for that ground water source only ifthe department approves the use of E. coli asa fecal indicator for source water monitoringunder this subsection (3)(A) and approves theuse of a single sample for meeting both thetriggered source water monitoring require-ments in this subsection (3)(A) and the repeatmonitoring requirements in 10 CSR 60-4.022(8). If the repeat sample collected fromthe ground water source is E. coli positive,the system must comply with paragraph(3)(A)3. of this rule.

3. Additional requirements. If the depart-ment does not require corrective action underparagraph (4)(A)2. of this rule for a fecal indi-cator-positive source water sample collected



under paragraph (3)(A)2. of this rule that isnot invalidated under subsection (3)(D) of thisrule, the system must collect five (5) addition-al source water samples from the same sourcewithin twenty-four (24) hours of being notifiedof the fecal indicator-positive sample.

4. Consecutive systems. In addition tothe other requirements of this subsection(3)(A), a consecutive ground water systemthat has a total coliform-positive sample col-lected under 10 CSR 60-4.022(4)-(7) mustnotify the wholesale system(s) within twenty-four (24) hours of being notified of the totalcoliform-positive sample.

5. Wholesale systems. In addition to theother requirements of this subsection (3)(A),a wholesale ground water system thatreceives notice from a consecutive system itserves that a sample collected under 10 CSR60-4.022(4)-(7) is total coliform-positivemust, within twenty-four (24) hours of beingnotified, collect a sample from its groundwater source(s) under paragraph (3)(A)2. ofthis rule and analyze it for a fecal indicatorunder subsection (3)(C) of this rule. If thissample is fecal indicator-positive, the systemmust notify all consecutive systems served bythat ground water source of the fecal indica-tor source water positive within twenty-four(24) hours of being notified of the monitoringresult and must meet the requirements ofparagraph (3)(A)3. of this rule.

6. Exceptions to triggered source watermonitoring requirements. A ground watersystem is not required to comply with thesource water monitoring requirements of thissubsection (3)(A) if either of the followingconditions exists:

A. The department determines, anddocuments in writing, that the total coliform-positive sample collected under 10 CSR 60-4.022(4)-(7) is caused by a distribution sys-tem deficiency; or

B. The total coliform-positive samplecollected under 10 CSR 60-4.022(4)-(7) iscollected at a location that meets departmentcriteria for distribution system conditions thatwill cause total coliform-positive samples.

(B) Assessment Source Water Monitoring.If directed by the department, ground watersystems must conduct assessment source watermonitoring that meets department-determinedrequirements. A ground water system con-ducting assessment source water monitoringmay use a triggered source water sample col-lected under paragraph (3)(A)2. of this rule tomeet the requirements of this subsection. Thedepartment may require any combination of—

1. Collection of a total of twelve (12)ground water source samples that representeach month the system provides ground waterto the public;

2. Collection of samples from each wellunless the system obtains written departmentapproval to conduct monitoring at one (1) ormore wells within the ground water systemthat are representative of multiple wells usedby that system and that draw water from thesame hydrogeologic setting;

3. Collection of a standard sample vol-ume of at least one hundred milliliters (100mL) for fecal indicator analysis regardless ofthe fecal indicator or analytical method used;

4. Analysis of all ground water sourcesamples using one (1) of the analytical meth-ods listed in paragraph (3)(C)2. of this rulefor the presence of E. coli, enterococci, orcoliphage;

5. Collection of ground water sourcesamples at a location prior to any treatment ofthe ground water source unless the depart-ment approves a sampling location after treat-ment; or

6. Collection of ground water sourcesamples at the well itself unless the system’sconfiguration does not allow for sampling atthe well itself and the department approves analternate sampling location that is representa-tive of the water quality of that well.

(C) Analytical Methods.1. A ground water system subject to the

source water monitoring requirements of sub-section (3)(A) of this rule must collect a stan-dard sample volume of at least one hundredmilliliters (100 mL) for fecal indicator analy-sis regardless of the fecal indicator or analyt-ical method used.

2. A ground water system must analyzeall ground water source samples collectedunder subsection (3)(A) of this rule usingone (1) of the analytical methods listed inthe Environmental Protection Agency’sCode of Federal Regulations, 40 CFR141.402, published February 13, 2013. Thisdocument is incorporated by reference with-out any later amendments or modifications.To obtain a copy, contact the U.S.Government Printing Office at 732 NorthCapitol Street NW, Washington D.C.,20401, toll free at (866) 512-1800 or by vis-iting https://bookstore.gpo.gov.

(D) Invalidation of a Fecal Indicator-Posi-tive Ground Water Source Sample.

1. A ground water system may obtaindepartment invalidation of a fecal indicator-positive ground water source sample collect-ed under subsection (3)(A) of this rule onlyunder the following conditions:

A. The system provides the depart-ment with written notice from the laboratorythat improper sample analysis occurred; or

B. The department determines anddocuments in writing that there is substantialevidence that a fecal indicator-positive

ground water source sample is not related tosource water quality.

2. If the department invalidates a fecalindicator-positive ground water source sam-ple, the ground water system must collectanother source water sample under subsec-tion (3)(A) of this rule within twenty-four(24) hours of being notified by the depart-ment of its invalidation decision and have itanalyzed for the same fecal indicator listed in40 CFR 141.402. The department may extendthe twenty-four (24)-hour time limit on acase-by-case basis if the system cannot collectthe source water sample within twenty-four(24) hours due to circumstances beyond itscontrol. In the case of an extension, thedepartment will specify how much time thesystem has to collect the sample.

(E) Sampling Location.1. Any ground water source sample

required under subsection (3)(A) of this rulemust be collected at a location prior to anytreatment of the ground water source unlessthe department approves a sampling locationafter treatment.

2. If the system’s configuration does notallow for sampling at the well itself, the sys-tem may collect a sample at a department-approved location to meet the requirements ofsubsection (3)(A) of this rule if the sample isrepresentative of the water quality of thatwell.

(F) New Sources. If directed by the depart-ment, a ground water system that places anew ground water source into service afterNovember 30, 2009, must conduct assess-ment source water monitoring under subsec-tion (3)(B) of this rule. If directed by thedepartment, the system must begin monitor-ing before the ground water source is used toprovide water to the public.

(G) Public Notification. A ground watersystem with a ground water source samplecollected under subsection (3)(A) or (3)(B) ofthis rule that is fecal indicator-positive andthat is not invalidated under subsection(3)(D) of this rule, including consecutive sys-tems served by the ground water source, mustconduct Tier 1 public notification under 10CSR 60-8.010.

(H) Monitoring Violations. Failure to meetthe requirements of subsections (3)(A)–(F) ofthis rule is a monitoring violation andrequires the ground water system to provideTier 3 public notification under 10 CSR 60-8.010.

(4) Treatment Technique Requirements.(A) Ground Water Systems with Signifi-

cant Deficiencies or Source Water Fecal Con-tamination.

1. The treatment technique requirements


Secretary of State


of this rule must be met by ground water sys-tems when a significant deficiency is identi-fied or when a ground water source samplecollected under paragraph (3)(A)3. of thisrule is fecal indicator-positive.

2. If directed by the department, aground water system with a ground watersource sample collected under paragraph(3)(A)3., paragraph (3)(A)4., or subsection(3)(B) that is fecal indicator-positive mustcomply with the treatment technique require-ments of this section (4).

3. When a significant deficiency is iden-tified at a public water system that uses bothground water and surface water or groundwater under the direct influence of surfacewater, the system must comply with provi-sions of this subsection (4)(A) except in caseswhere the department determines that the sig-nificant deficiency is in a portion of the dis-tribution system that is served solely by sur-face water or ground water under the directinfluence of surface water.

4. Unless the department directs theground water system to implement a specificcorrective action, the ground water systemmust consult with the department regardingthe appropriate corrective action within thir-ty (30) days of receiving written notice fromthe department of a significant deficiency,written notice from a laboratory that a groundwater source sample collected under para-graph (3)(A)3. of this rule was found to befecal indicator-positive, or direction from thedepartment that a fecal indicator-positivesample collected under paragraph (3)(A)2.,paragraph (3)(A)4., or subsection (3)(B) ofthis rule requires corrective action. For thepurposes of this rule, significant deficienciesinclude but are not limited to defects indesign, operation, or maintenance, or a fail-ure or malfunction of the sources, treatment,storage, or distribution system that thedepartment determines are causing, or havepotential for causing, the introduction of con-tamination into the water delivered to con-sumers. Such significant deficiencies mayinclude, but may not be limited to, the fol-lowing:

A. For the source, any improperlyconstructed, sealed, or inadequately screenedopening in the well head;

B. For treatment—(I) Failure to perform and record

the results of sufficient analyses to maintaincontrol of treatment process or water quality;

(II) Systems required to provide 4-log virus inactivation or removal that do notmeet disinfection concentration and detentiontime requirements; or

(III) Systems that are required todisinfect that do not have standby redundant

disinfection facilities;C. For distribution systems—

(I) The existence of a known unpro-tected cross-connection;

(II) Widespread or persistent lowpressure events as defined in 10 CSR 60-4.080(8);

(III) Submerged automatic airrelease valves or uncapped manual air releasevalves; or

(IV) Failure to properly disinfectnew or newly-repaired water mains;

D. For finished water storage—(I) The existence of any unprotect-

ed, inadequately protected, or improperlyconstructed opening in a storage facility; or

(II) Evidence that the water in thestorage facility has been contaminated (forexample, feathers or nesting materials in anoverflow pipe or positive bacteria samples);

E. For pumps or pump facilities andcontrols, repeated or persistent low pressurescaused by pump or pump control problems orinadequate pump capacity;

F. For monitoring, reporting, or dataverification—

(I) Falsification of monitoring orreporting records; or

(II) Failure to maintain systemrecords required under 10 CSR 60-9.010;

G. For water system management oroperations, failure to address significant defi-ciencies listed in the most recent inspectionor sanitary survey report; and

H. For operator compliance—(I) Lack of properly certified chief

operator in responsible charge of the treat-ment facility as required under 10 CSR 60-14.010(4); or

(II) Lack of properly certified chiefoperator in responsible charge of the distri-bution facility as required under 10 CSR 60-14.010(4).

5. Within one hundred twenty (120) days(or earlier if directed by the department) ofreceiving written notification from thedepartment of a significant deficiency, writtennotice from a laboratory that a ground watersource sample collected under paragraph(3)(A)3. of this rule was found to be fecalindicator-positive, or direction from thedepartment that a fecal indicator-positivesample collected under paragraph (3)(A)2.,paragraph (3)(A)4., or subsection (3)(B) ofthis rule requires corrective action, theground water system must either—

A. Have completed corrective actionin accordance with applicable departmentplan review processes or other departmentguidance or direction, if any, includingdepartment-specified interim measures; or

B. Be in compliance with a depart-

ment-approved corrective action plan andschedule subject to the following conditions:

(I) Any subsequent modificationsto a department-approved corrective actionplan and schedule must be approved by thedepartment; and

(II) If the department specifiesinterim measures for protection of the publichealth pending department approval of thecorrective action plan and schedule or pend-ing completion of the corrective action plan,the system must comply with these interimmeasures as well as with any schedule speci-fied by the department.

6. Corrective action alternatives.Ground water systems that meet the condi-tions of paragraph (4)(A)1. or (4)(A)2. of thisrule must implement one (1) or more of thefollowing corrective action alternatives underthe direction and approval of the department:

A. Correct all significant deficien-cies;

B. Provide an alternate source ofwater;

C. Eliminate the source of contamina-tion; or

D. Provide treatment that reliablyachieves at least 4-log treatment of virusesbefore or at the first customer for the groundwater source.

7. Special notice to the public of signif-icant deficiencies or source water fecal con-tamination.

A. In addition to the applicable publicnotification requirements of 10 CSR 60-8.010, a community ground water system thatreceives notice from the department of a sig-nificant deficiency or notification of a fecalindicator-positive ground water source sam-ple that is not invalidated by the departmentunder subsection (3)(D) of this rule mustinform the public served by the water systemunder 10 CSR 60-8.030(2)(H)6. of the fecalindicator-positive source sample or of anysignificant deficiency that has not been cor-rected. The system must continue to informthe public annually until the significant defi-ciency is corrected or the fecal contaminationin the ground water source is determined bythe department to be corrected under para-graph (4)(A)5. of this rule.

B. In addition to the applicable publicnotification requirements of 10 CSR 60-8.010, a non-community ground water systemthat receives notice from the department of asignificant deficiency must inform the publicserved by the water system in a mannerapproved by the department of any significantdeficiency that has not been corrected withintwelve (12) months of being notified by thedepartment, or earlier if directed by thedepartment. The system must continue to



inform the public annually until the signifi-cant deficiency is corrected.

(I) The information must include:(a) The nature of the significant

deficiency and the date the significant defi-ciency was identified by the department;

(b) The department-approvedplan and schedule for correction of the sig-nificant deficiency, including interim mea-sures, progress to date, and any interim mea-sures completed; and

(c) For systems with a large pro-portion of non-English speaking consumers,as determined by the department, informationin the appropriate language(s) regarding theimportance of the notice or a telephone num-ber or address where consumers may contactthe system to obtain a translated copy of thenotice or assistance in the appropriate lan-guage.

(II) If directed by the department, anoncommunity water system with significantdeficiencies that have been corrected mustinform its customers of the significant defi-ciencies, how the deficiencies were correct-ed, and the dates of correction.

(B) Compliance Monitoring.1. Existing ground water sources. A

ground water system that is not required tomeet the source water monitoring require-ments of this rule for any ground watersource because it provides at least 4-log treat-ment of viruses before or at the first customerfor any ground water source beforeDecember 1, 2009, must notify the depart-ment in writing that it provides at least 4-logtreatment of viruses before or at the first cus-tomer for the specified ground water sourceand begin compliance monitoring in accor-dance with paragraph (4)(B)3. of this rule byDecember 1, 2009. Notification to thedepartment must include engineering, opera-tional, or other information that the depart-ment requests to evaluate the submission. Ifthe system subsequently discontinues 4-logtreatment of viruses before or at the first cus-tomer for a ground water source, the systemmust conduct ground water source monitor-ing as required under section (3) of this rule.

2. New ground water sources. A groundwater system that places a ground watersource in service after November 30, 2009,that is not required to meet the source watermonitoring requirements of this rule becausethe system provides at least 4-log treatment ofviruses before or at the first customer for theground water source must comply with thefollowing:

A. The system must notify the depart-ment in writing that it provides at least 4-logtreatment of viruses before or at the first cus-tomer for the ground water source.

Notification to the department must includeengineering, operational, or other informa-tion that the department requests to evaluatethe submission;

B. The system must conduct compli-ance monitoring as required under paragraph(4)(B)3. of this rule within thirty (30) days ofplacing the source in service; and

C. The system must conduct groundwater source monitoring under section (3) ofthis rule if the system subsequently discontin-ues 4-log treatment of viruses before or at thefirst customer for the ground water source.

3. Monitoring requirements. A groundwater system subject to the requirements ofsubsection (4)(A), or paragraph (4)(B)1. or(4)(B)2. of this rule must monitor the effec-tiveness and reliability of treatment for thatground water source before or at the first cus-tomer as follows:

A. Chemical disinfection. (I) A ground water system that

serves greater than three thousand three hun-dred (3,300) people must continuously mon-itor the residual disinfectant concentrationusing analytical methods specified in 10 CSR60-5.010(5) at a location approved by thedepartment and must record the lowest resid-ual disinfectant concentration each day thatwater from the ground water source is servedto the public. The ground water system mustmaintain the department-determined residualdisinfectant concentration every day theground water system serves water from theground water source to the public. If there isa failure in the continuous monitoring equip-ment, the ground water system must conductgrab sampling every four (4) hours until thecontinuous monitoring equipment is returnedto service. The system must resume continu-ous residual disinfectant monitoring withinfourteen (14) days.

(II) A ground water system thatserves three thousand three hundred (3,300)or fewer people must monitor the residualdisinfectant concentration using analyticalmethods specified in 10 CSR 60-5.010(5) at alocation approved by the department andrecord the residual disinfection concentrationeach day that water from the ground watersource is served to the public. The groundwater system must maintain the department-determined residual disinfectant concentra-tion every day the ground water system serveswater from the ground water source to thepublic. The ground water system must take adaily grab sample during the hour of peakflow or at another time specified by thedepartment. If any daily grab sample mea-surement falls below the department-deter-mined residual disinfectant concentration, theground water system must take follow-up

samples every four (4) hours until the residu-al disinfectant concentration is restored to thedepartment-determined level. Alternatively, aground water system that serves three thou-sand three hundred (3,300) or fewer peoplemay monitor continuously and meet therequirements in part (I) of this subparagraph(4)(B)3.A.

B. Membrane filtration. A groundwater system that uses membrane filtration tomeet the requirements of this rule must mon-itor the membrane filtration process in accor-dance with all department-specified monitor-ing requirements and must operate the mem-brane filtration in accordance with all depart-ment-specified compliance requirements. Thedepartment will consider the manufacturer’srecommendations and guidelines as well asstandard industry practices in setting moni-toring and compliance requirements. Aground water system that uses membrane fil-tration is in compliance with the requirementto achieve at least 4-log removal of viruseswhen—

(I) The membrane has an absolutemolecular weight cut-off, or an alternateparameter that describes the exclusion char-acteristics of the membrane, that can reliablyachieve at least 4-log removal of viruses;

(II) The membrane process is oper-ated in accordance with department-specifiedcompliance requirements; and

(III) The integrity of the membraneis intact.

C. Alternative treatment. A groundwater system that uses a department-approvedalternative treatment to meet the require-ments of this rule by providing at least 4-logtreatment of viruses before or at the first cus-tomer must monitor the alternative treatmentin accordance with all department-specifiedmonitoring requirements and operate thealternative treatment in accordance with allcompliance requirements that the departmentdetermines to be necessary to achieve at least4-log treatment of viruses. The departmentwill consider the manufacturer’s recommen-dations and guidelines as well as standardindustry practices in setting monitoring andcompliance requirements for the approvedalternative treatment.

(C) Discontinuing Treatment. A groundwater system may discontinue 4-log treatmentof viruses before or at the first customer fora ground water source if the departmentdetermines and documents in writing that 4-log treatment of viruses is no longer neces-sary for that ground water source. A systemthat discontinues 4-log treatment of viruses issubject to the source water monitoring andanalytical methods requirements of section(3) of this rule.


Secretary of State


(D) Failure to meet the monitoring require-ments of this section is a monitoring violationand requires the ground water system to pro-vide public notification under section 10 CSR60-8.010(4) (Tier 3 notice).

(5) Treatment Technique Violations forGround Water Systems.

(A) A ground water system with a signifi-cant deficiency is in violation of the treatmenttechnique requirement if, within one hundredtwenty (120) days (or earlier if directed bythe department) of receiving written noticefrom the department of the significant defi-ciency, the system—

1. Does not complete corrective actionin accordance with any applicable departmentplan review processes or other departmentguidance and direction, including depart-ment-specified interim actions and measures;or

2. Is not in compliance with a depart-ment-approved corrective action plan andschedule.

(B) Unless the department invalidates afecal indicator-positive ground water sourcesample under subsection (3)(D) of this rule, aground water system is in violation of thetreatment technique requirement if, withinone hundred twenty (120) days (or earlier ifdirected by the department) of meeting theconditions of paragraph (4)(A)1. or (4)(A)2.of this rule, the system—

1. Does not complete corrective actionin accordance with any applicable departmentplan review processes or other departmentguidance and direction, including depart-ment-specified interim measures; or

2. Is not in compliance with a depart-ment-approved corrective action plan andschedule.

(C) A ground water system subject to therequirements of paragraph (4)(B)3. of thisrule that fails to maintain at least 4-log treat-ment of viruses before or at the first customerfor a ground water source is in violation ofthe treatment technique requirement if thefailure is not corrected within four (4) hoursof determining the system is not maintainingat least 4-log treatment of viruses before or atthe first customer.

(D) Ground water system must give publicnotification under section 10 CSR 60-8.010(3)(Tier 2 notice) for the treatment techniqueviolations specified in this section.

(6) Reporting Requirements. Reportingrequirements are in 10 CSR 60-7.010Reporting Requirements.

(7) Record-Keeping Requirements. Record-keeping requirements are in 10 CSR 60-9.010

Requirements for Maintaining Public WaterSystem Records.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed April 14, 2010, effectiveDec. 30, 2010. Amended: Filed Aug. 12,2015, effective March 30, 2016. Amended:Filed June 13, 2018, effective Feb. 28, 2019.

*Original authority: 640.100, RSMo 1939, amended1978, 1981, 1982, 1988, 1989, 1992, 1993, 1995, 1996,1998, 1999, 2002, 2006, 2012, 2014.

10 CSR 60-4.030 Maximum InorganicChemical Contaminant Levels, ActionLevels and Monitoring Requirements

PURPOSE: This rule establishes maximumcontaminant levels, action levels and moni-toring requirements for inorganic contami-nants.

(1) Maximum Contaminant Levels (MCL) orAction Levels.

(A) The maximum contaminant or actionlevel listed as follows for inorganic chemicals1.–17. apply to community water systems.The maximum contaminant or action levellisted as follows for inorganic chemicals 1.–9. and 11.–17. apply to nontransient noncom-munity water systems. The maximum con-taminant or action level listed as follows forinorganic chemicals 13.–15. apply to tran-sient noncommunity water systems:

MaximumContaminant

Contaminant Level (MCL)1. Antimony 0.006 mg/l 2. Arsenic 0.05 mg/l (until Jan.

23, 2006)0.010 mg/l (effective

Jan. 23, 2006)3. Asbestos 7 million fibers/liter

(longer than 10 μm in length)

4. Barium 2 mg/l5. Beryllium 0.004 mg/l 6. Cadmium 0.005 mg/l 7. Chromium 0.1 mg/l8. Copper * (See 10 CSR 60-

15.010(3)(B).)9. Cyanide 0.2 mg/l

10. Fluoride 4.0 mg/l11. Lead * (See 10 CSR 60-

15.010(3)(A).)12. Mercury 0.002 mg/l 13. Nitrate 10 mg/l (as nitrogen) 14. Nitrite 1 mg/l (as nitrogen)15. Total Nitrate

and Nitrite 10 mg/l (as nitrogen) 16. Selenium 0.05 mg/l 17. Thallium 0.002 mg/l

*Indicates action levels rather than maximumcontaminant levels.

(B) Nitrate levels not to exceed twenty (20)mg/l may be allowed in a noncommunitywater system if the supplier of water demon-strates to the satisfaction of the departmentthat all of the following factors apply to thesituation:

1. Such water will not be available tochildren under six (6) months of age;

2. The noncommunity water system ismeeting the public notification requirementsunder 10 CSR 60-8.010(9), including contin-uous posting of the fact that nitrate levelsexceed ten (10) mg/l and the potential healtheffects of exposure;

3. Local and state public health authori-ties will be notified annually of nitrate levelsthat exceed ten (10) mg/l; and

4. No adverse health effects shall result.

(2) Monitoring Frequency. (A) Asbestos. The frequency of monitoring

to determine compliance with the maximumcontaminant level (MCL) for asbestos speci-fied in section (1) of this rule shall be con-ducted as follows:

1. Each community and nontransientnoncommunity water system is required tomonitor for asbestos during the first three(3)-year compliance period of each nine (9)-year compliance cycle;

2. If monitoring data collected afterJanuary 1, 1990, are generally consistentwith the requirements of subsection (2)(A) ofthis rule, then the state may allow systems touse those data to satisfy the monitoringrequirement for the initial three (3)-year com-pliance period;

3. Waivers. A. The system may apply to the

department for a use waiver as described in10 CSR 60-6.060(2). If the department grantsthe waiver, the system is not required to mon-itor while the waiver is effective. A waiverremains in effect until the completion of thethree (3)-year compliance period and must berenewed for subsequent compliance periods.Systems not receiving a waiver must monitorin accordance with the provisions of para-graph (2)(A)1. of this rule.

B. The department may grant a waiv-er based on the potential asbestos contamina-tion of the water source and the use ofasbestos-cement pipe for finished water dis-tribution and the corrosive nature of thewater;

4. Increased and decreased monitoring. A. A system that is out of compliance

with the MCL as determined in section (6) ofthis rule shall monitor quarterly beginning inthe next quarter after the violation occurs.



B. The department may decrease thequarterly monitoring requirement to the fre-quency specified in paragraph (2)(A)1. of thisrule provided the department has determinedthat the analytical results for the system arereliably and consistently less than the MCL.In no case can the department make thisdetermination unless a groundwater systemtakes a minimum of two (2) quarterly samplesand a surface (or combined surface/ground)water system takes a minimum of four (4)quarterly samples; and

5. Sample collection. A. A system vulnerable to asbestos

contamination due solely to corrosion ofasbestos-cement pipe shall take at least one(1) sample at a tap served by asbestos-cementpipe and under conditions where asbestoscontamination is most likely to occur.

B. A system vulnerable to asbestoscontamination due solely to source watershall monitor in accordance with the provi-sion of section (4) of this rule.

C. A system vulnerable to asbestoscontamination due both to its source watersupply and corrosion of asbestos-cement pipeshall take at least one (1) sample at a tapserved by asbestos-cement pipe and underconditions where asbestos contamination ismost likely to occur.

(B) Inorganic Chemicals. Community andnontransient noncommunity water systemsshall monitor for antimony, arsenic, barium,beryllium, cadmium, chromium, cyanide,fluoride, mercury, nickel, selenium and thal-lium as set forth here.

1. Groundwater systems shall take one(1) sample at each sampling point duringeach three (3)-year compliance period begin-ning in the initial compliance period. Surfacewater systems (or combined surface/ground)shall take one (1) sample annually at eachsampling point beginning in the initial com-pliance period.

2. Waivers. A. The system may apply to the

department for a susceptibility waiver asdescribed in 10 CSR 60-6.060(3). If thedepartment grants the waiver, the system isrequired to take a minimum of one (1) sam-ple while the waiver is effective. The termduring which the waiver is effective shall notexceed one (1) nine (9)-year compliancecycle. Systems not receiving a waiver mustmonitor in accordance with the provisions ofparagraph (2)(B)1. of this rule.

B. The department may grant a waiv-er provided surface water systems have mon-itored annually for at least three (3) years andgroundwater systems have conducted a mini-mum of three (3) rounds of monitoring. Atleast one (1) sample shall have been taken

since January 1, 1990. Both surface andground water systems shall demonstrate thatall previous analytical results were reliablyand consistently less than the MCL. Systemsthat use a new water source are not eligiblefor a waiver until three (3) rounds of moni-toring from the new source have been com-pleted.

C. In determining the appropriatereduced monitoring frequency, the depart-ment shall consider the reported concentra-tions from all previous monitoring, thedegree of variation in reported concentrationsand other factors which may affect contami-nant concentrations (such as changes ingroundwater pumping rates, changes in thesystem’s configuration, changes in the sys-tem’s operating procedures, or changes instream flows or characteristics).

D. A decision by the department togrant a waiver shall be made in writing andshall set forth the basis for the determination.The determination may be initiated by thedepartment or upon an application by thepublic water system. The public water systemshall specify the basis for its request. Thedepartment shall review and, where appropri-ate, revise its determination of the appropri-ate monitoring frequency when the systemsubmits new monitoring data or when otherdata relevant to the system’s appropriate mon-itoring frequency become available.

E. The department may grant a waiv-er for monitoring for cyanide, if the depart-ment determines that the system is not vul-nerable due to lack of proximity to any indus-trial source of cyanide.

3. Increased and decreased monitoring. A. Systems which exceed the MCLs

as calculated in section (6) of this rule shallmonitor quarterly beginning in the next quar-ter after the violation occurs.

B. Where the results of sampling forantimony, arsenic, asbestos, barium, berylli-um, cadmium, chromium, cyanide, fluoride,mercury, nickel, selenium, or thallium indi-cate an exceedance of the maximum contam-inant level, the department may require thatone (1) additional sample be collected assoon as possible after the initial sample wastaken (but not to exceed two (2) weeks) at thesame sampling point.

C. The department may decrease thequarterly monitoring requirement to the fre-quencies specified in paragraph (2)(B)1. ofthis rule provided it has determined that theanalytical results for the system are reliablyand consistently below the MCL. In no casecan the department make this determinationunless a groundwater system takes a mini-mum of two (2) quarterly samples and a sur-face water system (or combined surface/

ground) takes a minimum of four (4) quarter-ly samples.

D. All new systems or systems thatuse a new source of water that begin opera-tion after January 22, 2004 must demonstratecompliance with the MCL within a period oftime specified by the department. The sys-tem must also comply with the initial sam-pling frequencies specified by the departmentto ensure a system can demonstrate compli-ance with the MCL. Routine and increasedmonitoring frequencies shall be conducted inaccordance with the requirements in this sec-tion (2).

E. For systems which are conductingmonitoring at a frequency greater than annu-al, compliance with the maximum contami-nant levels for antimony, arsenic, asbestos,barium, beryllium, cadmium, chromium,cyanide, fluoride, mercury, nickel, selenium,or thallium is determined by a running annu-al average at any sampling point. If the aver-age at any sampling point is greater than theMCL, then the system is out of compliance.If any one (1) sample would cause the annu-al average to be exceeded, then the system isout of compliance immediately. Any samplebelow the method detection limit shall be cal-culated at zero (0) for the purpose of deter-mining the annual average. If a system fails tocollect the required number of samples, com-pliance (average concentration) will be basedon the total number of samples collected.

F. For systems which are monitoringannually, or less frequently, and whose sam-ple exceeds one-half (1/2) the MCL for anti-mony, arsenic, asbestos, barium, beryllium,cadmium, chromium, cyanide, fluoride, mer-cury, nickel, selenium, or thallium, the sys-tem must begin quarterly monitoring. Thesystem will not be in violation of the MCLuntil is has completed one (1) year of quar-terly monitoring. If any sample result willcause the running annual average to exceedthe MCL at any sampling point, the system isout of compliance with the MCL. If a systemfails to collect the required number of sam-ples, compliance (average concentration) willbe based on the total number of samples col-lected.

G. Arsenic sampling results will bereported to the nearest 0.001 mg/l.

(C) Nitrate. All public water systems (com-munity; nontransient noncommunity; andtransient noncommunity) shall monitor todetermine compliance with the MCL fornitrate specified in section (1) of this rule.The frequency of monitoring shall be con-ducted as follows:

1. Groundwater systems. A. All public water systems (communi-

ty; nontransient noncommunity; and transient


Secretary of State


noncommunity) served by groundwater sys-tems shall monitor annually beginning in theinitial compliance period.

B. The repeat monitoring frequencyfor groundwater systems shall be quarterlyfor at least one (1) year following any one (1)sample in which the concentration is greaterthan or equal to fifty percent (≥50%) of theMCL.

C. The department may allow agroundwater system to reduce the samplingfrequency to an annual basis after four (4)consecutive quarterly samples are reliablyand consistently less than fifty percent(<50%) of the MCL.

D. After a round of quarterly sam-pling is completed, a system which is moni-toring annually shall take subsequent samplesduring the quarter(s) which previously result-ed in the highest analytical result; and

2. Surface water systems. A. All public water systems (commu-

nity; nontransient noncommunity; and tran-sient noncommunity) served by a surfacewater system shall monitor quarterly begin-ning in the initial compliance period.

B. The department may allow a sur-face water system to reduce the sampling fre-quency to annually if all analytical resultsfrom four (4) consecutive quarters are lessthan fifty percent (<50%) of the MCL.

C. A surface water system shall returnto quarterly monitoring if any one (1) sampleis greater than or equal to fifty percent(≥50%) of the MCL.

D. After a round of quarterly sam-pling is completed, a system which is moni-toring annually shall take subsequent samplesduring the quarter(s) which previously result-ed in the highest analytical result.

(D) Nitrite. All public water systems (com-munity; nontransient noncommunity; andtransient noncommunity) shall monitor todetermine compliance with the MCL fornitrite specified in section (1) of this rule.The frequency of monitoring shall be con-ducted as follows:

1. All public water systems shall takeone (1) sample at each sampling point in theinitial three (3)-year compliance period;

2. After the initial sample, systemswhere an analytical result for nitrite is lessthan fifty percent (<50%) of the MCL shallmonitor at the frequency specified by thedepartment; and

3. Repeat monitoring.A. The repeat monitoring frequency

for any water system shall be quarterly for atleast one (1) year following any one (1) sam-ple in which the concentration is greater thanor equal to fifty percent (≥50%) of theMCL.

B. The department may allow a sys-tem to reduce the sampling frequency toannually after determining the analyticalresults for the system are reliably and consis-tently less than the MCL.

C. Systems which are monitoringannually shall take each subsequent sampleduring the quarter(s) which previously result-ed in the highest analytical result.

(E) Lead and Copper. All community andnontransient noncommunity water systemsare required to monitor for lead and copper(see 10 CSR 60-15.070 for monitoring fre-quency, requirements and protocol for leadand copper).

(3) Monitoring Requirements. (A) Each public water system shall moni-

tor at the time designated by the departmentduring each three (3)-year compliance peri-od.

(B) Systems may apply to the departmentto conduct more frequent monitoring than theminimum monitoring frequencies specified inthis chapter.

(C) The department may require more fre-quent monitoring than specified in section (2)of this rule or may require confirmation sam-ples for positive and negative results at itsdiscretion.

(4) Monitoring Protocol. For the purpose ofdetermining compliance with MCLs, samplesmust be collected for analyses as follows:

(A) All public water systems shall take aminimum of one (1) sample at every entrypoint to the distribution system after anyapplication of treatment which is representa-tive of each source after treatment (called asampling point) beginning in the initial com-pliance period;

(B) The system shall take each sample atthe same sampling point unless conditionsmake another sampling point more represen-tative of each source or treatment plant; and

(C) If a system draws water from morethan one (1) source and the sources are com-bined before distribution, the system mustsample at an entry point to the distributionsystem during periods of normal operatingconditions (that is, when water is representa-tive of all sources being used).

(5) Confirmation Samples.(A) Where the results of sampling for anti-

mony, arsenic, asbestos, barium, beryllium,cadmium, chromium, cyanide, fluoride, mer-cury, selenium or thallium indicate anexceedance of the MCL, the department mayrequire that one (1) additional sample be col-lected as soon as possible after the initialsample was taken (but not to exceed two (2)

weeks) at the same sampling point. (B) Nitrate and Nitrite.

1. Where nitrate or nitrite samplingresults indicate an exceedance of the MCL,the system shall take a confirmation samplewithin twenty-four (24) hours of the system’sreceipt of notification of the analytical resultsof the first sample.

2. Systems unable to comply with thetwenty-four (24)-hour sampling requirementmust immediately notify persons served bythe public water system in accordance with 10CSR 60-8.010(2). Systems exercising thisoption must take and analyze a confirmationsample within two (2) weeks of notification ofthe analytical results of the first sample.

(C) If a department-required confirmationsample is taken for any contaminant, then theresults of the initial and confirmation sampleshall be averaged. The resulting average shallbe used to determine the system’s compliancein accordance with section (6) of this rule.The department has the discretion to deleteresults of obvious sampling errors.

(6) Compliance. Compliance with section (1)of this rule shall be determined based on theanalytical result(s) obtained at each samplingpoint.

(A) For systems which are conducting mon-itoring at a frequency greater than annual,compliance with the MCLs for antimony,arsenic, asbestos, barium, beryllium, cadmi-um, chromium, cyanide, fluoride, mercury,selenium or thallium is determined by a run-ning annual average at each sampling point. Ifthe average at any sampling point is greaterthan the MCL, then the system is out of com-pliance. If any one (1) sample would causethe annual average to be exceeded, then thesystem is out of compliance immediately.Any sample below the method detection limitshall be calculated at zero (0) for the purposeof determining the annual average.

(B) For systems which are monitoringannually, or less frequently, the system is outof compliance with the MCLs for antimony,arsenic, asbestos, barium, beryllium, cadmi-um, chromium, cyanide, fluoride, mercury,selenium or thallium if the level of a contam-inant at any sampling point is greater than theMCL. If a confirmation sample is required bythe department, the determination of compli-ance will be based on the average of the two(2) samples.

(C) Compliance with the MCLs for nitrateand nitrite is determined based on one (1)sample if the levels of these contaminants isbelow the MCLs. If the levels exceed theMCLs in the initial sample, a confirmationsample is required in accordance with sub-section (5)(B) of this rule and compliance



shall be determined based on the average ofthe initial and confirmation samples.

(D) All community and nontransient non-community water systems are required tomonitor for lead and copper (see 10 CSR 60-15.070 for compliance requirements if leadand copper action levels are exceeded).

(7) Public Notice. If the result of analysesindicates that the level of antimony, arsenic,asbestos, barium, beryllium, cadmium,chromium, cyanide, fluoride, mercury, sele-nium or thallium exceeds the MCL, the sup-plier of water must report to the departmentwithin seven (7) days.

(A) When the system is out of compliancefor antimony, asbestos, barium, beryllium,cadmium, chromium, cyanide, fluoride, mer-cury, selenium or thallium, as determined bysection (6) of this rule, the supplier of watermust notify the department as required by 10CSR 60-7.010 and give public notice asrequired by 10 CSR 60-8.010.

(B) When the system is out of compliancefor nitrate, nitrite or total nitrate and nitrite,as determined by section (6) of this rule, thesupplier of water must notify the departmentas required by 10 CSR 60-7.010 and give pub-lic notice as required by 10 CSR 60-8.010.

(C) When the system is out of compliancefor lead or copper as determined by 10 CSR60-15.070, 10 CSR 60-15.080 and 10 CSR60-15.090, the supplier of water must notifythe department as required by 10 CSR 60-7.020 and give public notice as required by10 CSR 60-8.010.

AUTHORITY: section 640.100, RSMo Supp.2002.* Original rule filed May 4, 1979,effective Sept. 14, 1979. Amended: FiledApril 14, 1981, effective Oct. 11, 1981.Amended: Filed Aug. 4, 1987, effective Jan.1, 1988. Rescinded and readopted: FiledMarch 31, 1992, effective Dec. 3, 1992.Amended: Filed Aug. 4, 1992, effective May6, 1993. Amended: Filed May 4, 1993, effec-tive Jan. 13, 1994. Amended: Filed Feb. 1,1996, effective Oct. 30, 1996. Amended:Filed March 17, 2003, effective Nov. 30,2003.


10 CSR 60-4.040 Maximum SyntheticOrganic Chemical Contaminant Levels andMonitoring Requirements

PURPOSE: This rule establishes maximumcontaminant levels and monitoring require-ments for synthetic organic chemical contam-

inants.

(1) The following are the maximum contami-nant levels (MCLs) for synthetic organicchemical contaminants.

Maximum Contaminant Level,

Contaminant Milligrams Per Liter1. Alachlor 0.0022. Atrazine 0.0033. Benzo(a)pyrene 0.00024. Carbofuran 0.045. Chlordane 0.0026. Dalapon 0.27. Di(2-ethylhexyl)

adipate 0.48. Dibromochloro-

propane (DBCP) 0.00029. Di(2-ethylhexyl)

phthlate 0.00610. Dinoseb 0.00711. Diquat 0.0212. Endothall 0.113. Endrin 0.00214. 2,4-D 0.0715. Ethylene dibromide

(EDB) 0.0000516. Glyphosate 0.717. Heptachlor 0.000418. Heptachlor epoxide 0.000219. Hexachlorobenzene 0.00120. Hexachlorocyclo-

pentadiene 0.0521. Lindane 0.000222. Methoxychlor 0.0423. Oxamyl (Vydate) 0.224. Picloram 0.525. Polychlorinated

biphenyls (PCBs) 0.0005 (as determined by Method508A only)

26. Pentachlorophenol 0.00127. Simazine 0.00428. Toxaphene 0.00329. 2,3,7,8-TCDD (Dioxin) 0.0000000330. 2,4,5-TP (Silvex) 0.05

(2) For the purpose of determining compli-ance with MCLs, a supplier of water mustcollect samples of the product water for anal-ysis as follows:

(A) During the initial three (3)-year com-pliance period, all community and nontran-sient noncommunity water systems must col-lect an initial round of four (4) consecutivequarterly samples unless a waiver has beengranted by the department. The departmentwill designate the year in which each systemsamples within this compliance period;

(B) All public water systems shall sample

at points in the distribution system represen-tative of each water source or at each entrypoint to the distribution system. The sam-pling point will be after the application oftreatment, if any. Each sample must be takenat the same sampling point unless conditionsmake another sampling point more represen-tative of each source or treatment plant;

(C) If the system draws water from morethan one (1) source and the sources are com-bined before distribution, the system mustsample at an entry point to the distributionsystem during periods of normal operatingconditions; and

(D) The department may require more fre-quent monitoring than specified in this sec-tion of the rule and may require confirmationsamples for positive or negative results, at itsdiscretion.

(3) If contaminants are not detected duringthe initial sampling as indicated in section (2)of this rule, systems may decrease their sam-pling frequency beginning in the next three(3)-year compliance period.

(A) Systems that serve greater than threethousand three hundred (>3,300) personsmay reduce their sampling frequencies to two(2) quarterly samples at each sampling pointin one (1) year in each compliance period.

(B) Systems that serve less than or equal to three thousand three hundred (≤3,300) per-sons may reduce their sampling frequenciesto one (1) sample in each compliance period.

(4) The department may allow sampling datacollected between January 1, 1990 andDecember 31, 1995, to satisfy the initial basesampling requirements, if the sampling wascompleted as required by subsections (2)(B)and (C) of this rule.

(5) If contaminants are detected in any sam-ple, then systems must sample quarterlybeginning in the next quarter at each sam-pling point which resulted in a detection.

(A) Groundwater systems must sample aminimum of two (2) quarters and surfacewater must sample a minimum of four (4)quarters to establish a baseline.

(B) If the MCL is exceeded as described insubsection (5)(E) or (F) of this rule, then sys-tems must sample quarterly beginning in thenext quarter. Systems must sample a mini-mum of four (4) quarters to establish a base-line.

(C) If the baseline indicates a system’s ana-lytical results are reliably and consistentlybelow the MCL, the department may reducethe system’s sampling frequency to annually.(Annual sampling must be conducted duringthe quarter which previously yielded the


Secretary of State


highest analytical result.)(D) Systems which have three (3) consecu-

tive annual samples with no detection of acontaminant may apply to the department fora waiver.

(E) If one (1) sampling point is in violationof an MCL, the system is in violation of theMCL.

1. For systems monitoring more thanonce per year, compliance with the MCL isdetermined by a running annual average ateach sampling point.

2. Systems monitoring annually or lessfrequently whose sample result exceeds theregulatory detection level as defined by 10CSR 60-5.010(6)(B) must begin quarterlysampling. The system will not be consideredin violation of the MCL until it has complet-ed one (1) year of quarterly sampling.

3. If any sample result will cause therunning annual average to exceed the MCL atany sampling point, the system is out of com-pliance with the MCL immediately.

4. If a system fails to collect the requirednumber of samples, compliance will be basedon the total number of samples collected.

5. If a sample result is less than thedetection limit, zero will be used to calculatethe annual average.

(F) If monitoring results in detection ofone (1) or more of certain related contami-nants (aldicarb, aldicarb sulfone, aldicarbsulfoxide and heptachlor, heptachlor epox-ide), then subsequent monitoring shall ana-lyze for all related contaminants.

(6) A public water system may apply to thedepartment for a waiver from required sam-pling. Systems are eligible for reduced moni-toring in the initial three (3)-year complianceperiod. The waiver is effective for one (1)compliance period. It must be renewed insubsequent compliance periods or the systemmust conduct sampling as required by sub-section (2)(A) of this rule.

(A) A public water system may apply to thedepartment for a use waiver for reduced mon-itoring from required sampling if previoususe of the chemical can be ruled out asrequired by 10 CSR 60-6.060(2).

(B) A public water system may apply to thedepartment for a susceptibility waiver forreduced monitoring contingent on the con-duct of a thorough vulnerability assessmentas required by 10 CSR 60-6.060(3).

(7) As determined by the department, a con-firmation sample may be required for eitherpositive or negative results. If a confirmationsample is used, the compliance determinationis based on the average of the results of boththe confirmation sample and the initial sam-

ple. The department has the discretion todelete results of obvious sampling errorsfrom this calculation.

(8) Any public water system violating MCLsor monitoring and reporting requirements forany of the contaminants listed in section (1)of this rule must notify the department with-in seven (7) days and give public notice asrequired by 10 CSR 60-8.010.

(9) Treatment Techniques. (A) All public water systems shall use

treatment techniques in lieu of MCLs forspecified contaminants.

(B) Each public water system must certifyannually in writing to the department (usingthird-party or manufacturers’ certification)that when acrylamide and epichlorohydrin areused in drinking water systems, the combina-tion (or product) of dose and monomer leveldoes not exceed the levels specified as fol-lows:

Acrylamide = 0.05% dosed at 1 part permillion (ppm) (or equivalent)Epichlorohydrin = 0.01% dosed at 20 ppm(or equivalent)

Certifications can rely on manufacturers orthird parties, as approved by the department.

(10) All new systems or systems that use anew source of water that begin operation afterJanuary 22, 2004 must demonstrate compli-ance with the MCL or treatment techniquewithin a period of time specified by thedepartment. The system must also complywith the initial sampling frequencies speci-fied by the department to ensure a system candemonstrate compliance with the MCL ortreatment technique. Routine and increasedmonitoring frequencies shall be conducted inaccordance with the requirements in section(5) of this rule.

AUTHORITY: section 640.100, RSMo Supp.2002.* Original rule filed May 4, 1979,effective Sept. 14, 1979. Amended: FiledApril 14, 1981, effective Oct. 11, 1981.Rescinded and readopted: Filed March 31,1992, effective Dec. 3, 1992. Amended: FiledMay 4, 1993, effective Jan. 13, 1994.Amended: Filed Feb. 1, 1996, effective Oct.30, 1996. Amended: Filed March 17, 2003,effective Nov. 30, 2003.


10 CSR 60-4.050 Maximum TurbidityLevels and Monitoring Requirements andFilter Backwash Recycling

PURPOSE: This rule establishes maximumcontaminant levels and monitoring require-ments for turbidity.

(1) Applicability. This rule applies to all pub-lic water systems that use surface water orground-water under the direct influence ofsurface water.

(2) Enhanced Turbidity Requirements.(A) Maximum Turbidity Levels.

1. Turbidity must be equal to or lessthan 0.3 turbidity units in at least ninety-fivepercent (95%) of the measurements takeneach month; and

2. There must be no more than one (1)turbidity unit in any one (1) measurement.

(B) The frequency of sampling shall be asset forth in 10 CSR 60-4.080(3).

(C) Reporting to the Department.1. If at any time the turbidity exceeds

one (1) nephelometric turbidity unit (NTU)in representative samples of filtered water ina system using conventional filtration treat-ment or direct filtration, the system mustinform the department as soon as possible,but no later than the end of the next businessday.

2. If at any time the turbidity in repre-sentative samples of filtered water exceedsthe maximum level set by the departmentunder subsection (2)(F) of this rule for filtra-tion technologies other than conventional fil-tration treatment, the system must inform thedepartment as soon as possible, but no laterthan the end of the next business day.

(D) Filtration Sampling Requirements forSurface Water Systems

1. A public water system using surfacewater or groundwater under the direct influ-ence of surface water that provides conven-tional filtration treatment must conduct con-tinuous monitoring of turbidity for each indi-vidual filter using an approved method in 10CSR 60-5.010 and must calibrate turbidime-ters using the procedure specified by themanufacturer. Systems must record theresults of individual filter monitoring everyfifteen (15) minutes.

2. If there is a failure in the continuousturbidity monitoring equipment, the systemmust conduct grab sampling every four (4)hours in lieu of continuous monitoring, untilthe turbidimeter is repaired and back on-line.A system has a maximum of five (5) workingdays after failure in the continuous monitor-ing equipment to repair the equipment beforethe system is in violation. With department



approval, systems serving less than ten thou-sand (10,000) people may be granted up tofourteen (14) days to repair the equipmentbefore the system is in violation.

(E) Lime Softening. 1. A system that uses lime softening may

acidify representative samples prior to analy-sis using a protocol approved by the depart-ment.

2. Systems that use lime softening mayapply to the department for alternativeexceedance levels for the levels specified in10 CSR 60-7.010(6)(B) if they can demon-strate that higher turbidity levels in individu-al filters are due to lime carryover only andnot due to degraded filter performance.

(F) Filtration Technologies Other ThanConventional Filtration Treatment.

1. A public water system may use a fil-tration technology other than conventionalfiltration if it demonstrates to the department,using pilot plant studies or other means, thatthe alternative filtration technology, includingdirect filtration, in combination with disin-fection treatment that meets the requirementsof 10 CSR 60-4.055, consistently achieves99.9 percent removal and/or inactivation ofGiardia lamblia cysts and 99.99 percentremoval and/or inactivation of viruses, andninety-nine percent (99%) removal ofCryptosporidium oocysts, and the departmentapproves the use of the filtration technology.

2. For each approval, the departmentwill set turbidity performance requirementsthat the system must meet at least ninety-fivepercent (95%) of the time and that the systemmay not exceed at any time at a level that con-sistently achieves 99.9 percent removaland/or inactivation of Giardia lamblia cysts,99.99 percent removal or inactivation ofviruses, or both, and 99 percent removal ofCryptosporidium oocysts.

(3) Filter Backwash Recycling.(A) Applicability. Any water treatment

plant proposed for construction or majormodification for a surface water or ground-water under the direct influence of surfacewater or direct filtration treatment and thatwill recycle spent filter backwash water,thickener supernatant, or liquids from dewa-tering processes must be designed to meet thefilter backwash recycling requirements of thissection.

(B) Reporting. A system must notify thedepartment in writing if the system recyclesspent filter backwash water, thickener super-natant, or liquids from dewatering processes.This notification must include, at a mini-mum, the following information:

1. A plant schematic showing the originof all flows which are recycled (including, but

not limited to, spent filter backwash water,thickener supernatant, and liquids fromdewatering processes), the hydraulic con-veyance used to transport them, and the loca-tion where they are reintroduced back intothe treatment plant; and

2. Typical recycle flow in gallons perminute (gpm), the highest observed plantflow experienced in the previous year (gpm),design flow for the treatment plant (gpm),and department-approved operating capacityfor the plant where the department has madesuch determinations.

(C) Treatment Technique Requirement.Any system that recycles spent filter back-wash water, thickener supernatant, or liquidsfrom dewatering processes must return theseflows through the processes of a system’sexisting conventional or direct filtration sys-tem or at an alternate location approved bythe department.

(D) Record Keeping. The system must col-lect and retain on file recycle flow informa-tion for review and evaluation by the depart-ment. This information shall include, but maynot be limited to:

1. A copy of the recycle notification andinformation submitted to the departmentunder subsection (3)(B) of this rule;

2. A list of all recycle flows and the fre-quency with which they are returned;

3. Average and maximum backwashflow rate through the filters and the averageand maximum duration of the filter backwashprocess in minutes;

4. Typical filter run length and a writtensummary of how filter run length is deter-mined;

5. The type of treatment provided for therecycle flow; and

6. Data on the physical dimensions ofthe equalization and/or treatment units, typi-cal and maximum hydraulic loading rates,type of treatment chemicals used and averagedose and frequency of use, and frequency atwhich solids are removed, if applicable.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed May 4, 1979, effectiveSept. 14, 1979. Amended: Filed April 14,1981, effective Oct. 11, 1981. Amended: FiledJuly 12, 1991, effective Feb. 6, 1992.Amended: Filed Feb. 1, 1996, effective Oct.30, 1996. Amended: Filed Dec. 15, 1999,effective Sept. 1, 2000. Amended: Filed Jan.16, 2002, effective Nov. 30, 2002. Amended:Filed March 17, 2003, effective Nov. 30,2003. Amended: Filed June 13, 2018, effec-tive Feb. 28, 2019.


10 CSR 60-4.052 Source Water Monitoringand Enhanced Treatment Requirements

PURPOSE: This rule establishes sourcewater monitoring requirements and enhancedtreatment for Cryptosporidium for surfacewater systems and systems under the directinfluence of surface water. These require-ments are in addition to requirements for fil-tration and disinfection in 10 CSR 60-4.050and 10 CSR 60-4.055. This rule adopts therequirements found in subpart W of 40 CFRpart 141.

(1) Enhanced Treatment for CryptosporidiumGeneral Requirements.

(A) The requirements of this rule arenational primary drinking water regulations.The regulations in this rule establish orextend treatment technique requirements inlieu of maximum contaminant levels forCryptosporidium. These requirements are inaddition to requirements for filtration anddisinfection in 10 CSR 60-4.050 and 10 CSR60-4.055.

(B) Applicability.1. The requirements of this rule apply to

all public water systems supplied by a surfacewater source and public water systems sup-plied by a ground water source under thedirect influence of surface water.

2. Wholesale systems, as defined in 10CSR 60-2.015, must comply with therequirements of this rule based on the popu-lation of the largest system in the combineddistribution system.

(C) Requirements. Systems subject to thisrule must comply with the following require-ments:

1. Systems must conduct an initial and asecond round of source water monitoring foreach plant that treats a surface water orground water under the direct influence ofsurface water (GWUDISW) source. Thismonitoring may include sampling forCryptosporidium, E. coli, and turbidity asdescribed in sections (2)–(6) of this rule, todetermine what level, if any, of additionalCryptosporidium treatment they must pro-vide;

2. Systems that plan to make a signifi-cant change to their disinfection practicemust develop disinfection profiles and calcu-late disinfection benchmarks, as described insections (8) and (9) of this rule;

3. Filtered systems must determine theirCryptosporidium treatment bin classificationas described in section (10) of this rule andprovide additional treatment forCryptosporidium, if required, as described insection (11) of this rule. Filtered systems mustimplement Cryptosporidium treatment


Secretary of State


according to the schedule in section (12) ofthis rule;

4. Systems required to provide addition-al treatment for Cryptosporidium must imple-ment microbial toolbox options that aredesigned and operated as described in sec-tions (13)–(18) of this rule; and

5. Systems must comply with the appli-cable record-keeping and reporting require-ments described in 10 CSR 60-7.010 and 10CSR 60-9.010.

(2) Source Water Monitoring Requirements. (A) Initial Round of Source Water Moni-

toring. Systems must conduct the followingmonitoring on the schedule in subsection(2)(C) of this rule unless they meet the mon-itoring exemption criteria in subsection(2)(D) of this rule.

1. Filtered systems serving at least tenthousand (10,000) people must sample theirsource water for Cryptosporidium, E. coli,and turbidity at least monthly for twenty-four(24) months.

2. Filtered systems serving fewer thanten thousand (10,000) people must sampletheir source water for E. coli at least onceevery two (2) weeks for twelve (12) months.

3. A filtered system serving fewer thanten thousand (10,000) people may avoid E.coli monitoring if the system notifies thedepartment that it will monitor forCryptosporidium as described in paragraph(2)(A)4. of this rule. The system must notifythe department no later than three (3) monthsprior to the date the system is otherwiserequired to start E. coli monitoring undersubsection (2)(C) of this rule.

4. Filtered systems serving fewer thanten thousand (10,000) people must sampletheir source water for Cryptosporidium atleast twice per month for twelve (12) monthsor at least monthly for twenty-four (24)months if they meet one (1) of the following,based on monitoring conducted under para-graphs (2)(A)2. and 3. of this rule.

A. For systems using lake or reservoirsources, the annual mean E. coli concentra-tion is greater than 10 E. coli/100 mL.

B. For systems using flowing streamsources, the annual mean E. coli concentra-tion is greater than 50 E. coli/100 mL.

C. The system does not conduct E.coli monitoring as described in paragraphs(2)(A)2. and 3. of this rule.

D. Systems using ground water underthe direct influence of surface water(GWUDISW) must comply with the require-ments of paragraph (2)(A)4. of this rulebased on the E. coli level that applies to thenearest surface water body. If no surfacewater body is nearby, the system must com-

ply based on the requirements that apply tosystems using lake/reservoir sources.

5. For filtered systems serving fewerthan ten thousand (10,000) people, thedepartment may approve monitoring for anindicator other than E. coli under paragraph(2)(A)2. of this rule. The department alsomay approve an alternative to the E. coli con-centration in subparagraph (2)(A)4.A., B., orD. of this rule to trigger Cryptosporidiummonitoring. This approval by the departmentmust be provided to the system in writing andmust include the basis for the department’sdetermination that the alternative indicatorand/or trigger level will provide a more accu-rate identification of whether a system willexceed the Bin 1 Cryptosporidium level insection (10) of this rule.

6. Systems may sample more frequentlythan required under this section if the sam-pling frequency is evenly spaced throughoutthe monitoring period.

(B) Second Round of Source Water Moni-toring. Systems must conduct a second roundof source water monitoring that meets therequirements for monitoring parameters, fre-quency, and duration described in subsection(2)(A) of this rule, unless they meet the mon-itoring exemption criteria in subsection(2)(D) of this rule. Systems must conduct thismonitoring on the schedule in subsection(2)(C) of this rule.

(C) Monitoring Schedule. Systems mustbegin the monitoring required in subsection(2)(A) and subsection (2)(B) of this rule nolater than the month beginning with the datelisted in this table—



(D) Monitoring Avoidance. 1. Filtered systems are not required to

conduct source water monitoring under thisrule if the system will provide a total of atleast 5.5-log of treatment forCryptosporidium, equivalent to meeting thetreatment requirements of Bin 4 in section(11) of this rule.

2. If a system chooses to provide thelevel of treatment in paragraph (2)(D)1. ofthis rule as applicable, rather than startsource water monitoring, the system mustnotify the department in writing no later thanthe date the system is otherwise required tosubmit a sampling schedule for monitoringunder section (3) of this rule. Alternatively,a system may choose to stop sampling at anypoint after it has initiated monitoring if itnotifies the department in writing that it willprovide this level of treatment. Systems mustinstall and operate technologies to providethis level of treatment by the applicable treat-ment compliance date in section (12) of thisrule.

(E) Plants Operating Only Part of the Year.Systems with plants that operate for only partof the year must conduct source water moni-toring in accordance with this rule, but withthe following modifications:

1. Systems must sample their sourcewater only during the months that the plantoperates unless the department specifiesanother monitoring period based on plantoperating practices; and

2. Systems with plants that operate lessthan six (6) months per year and that monitorfor Cryptosporidium must collect at least six(6) Cryptosporidium samples per year duringeach of two (2) years of monitoring. Samplesmust be evenly spaced throughout the periodthe plant operates.

(F) New Source Requirements.1. A system that begins using a new

source of surface water or GWUDISW afterthe system is required to begin monitoringunder subsection (2)(C) of this rule mustmonitor the new source on a schedule thedepartment approves. Source water monitor-ing must meet the requirements of this rule.The system must also meet the bin classifica-tion and Cryptosporidium treatment require-ments of sections (10) and (11) of this rule, asapplicable, for the new source on a schedulethe department approves.

2. The requirements of subsection (2)(F)of this rule apply to surface water systemsand ground water under the direct influenceof surface water systems that begin operationafter the monitoring start date applicable tothe system’s size under subsection (2)(C) ofthis rule.

3. The system must begin a secondround of source water monitoring no laterthan six (6) years following initial bin classi-fication under section (10) of this rule.

(G) Failure to collect any source watersample required under this section in accor-dance with the sampling schedule, samplinglocation, analytical method, approved labora-tory, and reporting requirements of sections(3) through (6) of this rule is a monitoringviolation.

(H) Grandfathering Monitoring Data.Systems may use (i.e., may “grandfather”)monitoring data collected prior to the appli-cable monitoring start date in subsection(2)(C) to meet the initial source water moni-toring requirements in subsection (2)(A) ofthis rule. Grandfathered data may substitutefor an equivalent number of months at theend of the monitoring period. All data sub-mitted under subsection (2)(H) must meet therequirements in section (7) of this rule.

(3) Sampling Schedules. (A) Systems required to conduct source

water monitoring under section (2) of thisrule must submit a sampling schedule thatspecifies the calendar dates when the systemwill collect each required sample.

1. Systems must submit sampling sched-ules no later than three (3) months prior tothe applicable date listed in subsection (2)(C)of this rule for each round of required moni-toring.

2. Systems serving at least ten thousand(10,000) people must submit their samplingschedule for the initial round of source watermonitoring under subsection (2)(A) of thisrule to the Environmental Protection Agency(EPA) electronically at the web address spec-ified by the EPA for this purpose. If a systemis unable to submit the sampling scheduleelectronically, the system may use an alterna-tive approach for submitting the samplingschedule that the EPA approves.

3. Systems serving fewer than ten thou-sand (10,000) people must submit their sam-pling schedules for the initial round of sourcewater monitoring in subsection (2)(A) of thisrule to the department.

4. Systems must submit sampling sched-ules for the second round of source watermonitoring in subsection (2)(B) of this rule tothe department.

5. If the EPA or the department does notrespond to a system regarding its samplingschedule, the system must sample at thereported schedule.

(B) Systems must collect samples withintwo (2) days before or two (2) days after thedates indicated in their sampling schedule(that is, within a five (5)-day period aroundthe schedule date) unless one (1) of the con-ditions of paragraph (3)(B)1. or 2. applies.

1. If an extreme condition or situationexists that may pose danger to the sample col-lector, or that cannot be avoided and causesthe system to be unable to sample in the


Secretary of State


Systems that serve:

Must begin the first round of source water monitoring no later than the month beginning:

And must begin the second round of source water monitoring no later than the month beginning:

At least 100,000 people October 1, 2006 April 1, 2015From 50,000 to 99,999 April 1, 2007 October 1, 2015 From 10,000 to 49,999 April 1, 2008 October 1, 2016 Fewer than 10,000 and monitor for E. coli

October 1, 2008 October 1, 2017

Fewer than 10,000 and monitor for Cryptosporidium (Applies to filtered systems that meet the conditions of paragraph (2)(A)3. of this rule.)

April 1, 2010 April 1, 2019

Source Water Monitoring Starting Dates Table

scheduled five (5)-day period, the systemmust sample as close to the scheduled date asis feasible unless the department approves analternative sampling date. The system mustsubmit an explanation for the delayed sam-pling date to the department concurrent withthe shipment of the sample to the laboratory.

2. If a system is unable to report a validanalytical result for a scheduled samplingdate due to equipment failure, loss of or dam-age to the sample, failure to comply with theanalytical method requirements, including thequality control requirements in 10 CSR 60-5.010, or the failure of an approved laborato-ry to analyze the sample, then the systemmust collect a replacement sample. The sys-tem must collect the replacement sample notlater than twenty-one (21) days after receivinginformation that an analytical result cannot bereported for the scheduled date unless thesystem demonstrates that collecting a replace-ment sample within this time frame is notfeasible or the department approves an alter-native resampling date. The system must sub-mit an explanation for the delayed samplingdate to the department concurrent with theshipment of the sample to the laboratory.

(C) Systems that fail to meet the criteria ofsubsection (3)(B) of this rule for any sourcewater sample required under section (2) ofthis rule must revise their sampling schedulesto add dates for collecting all missed samples.Systems must submit the revised schedule tothe department for approval prior to when thesystem begins collecting the missed samples.

(4) Sampling Locations. (A) Systems required to conduct source

water monitoring under section (2) of thisrule must collect samples for each plant thattreats a surface water or GWUDISW source.Where multiple plants draw water from thesame influent, such as the same pipe orintake, the department may approve one (1)set of monitoring results to be used to satisfythe requirements of section (2) of this rule forall plants.

(B) Systems must collect source watersamples prior to chemical treatment, such ascoagulants, oxidants, and disinfectants,unless the system meets the condition of para-graph (4)(B)1. of this rule.

1. The department may approve a systemto collect a source water sample after chemi-cal treatment. To grant this approval, thedepartment must determine that collecting asample prior to chemical treatment is notfeasible for the system and that the chemicaltreatment is unlikely to have a significantadverse effect on the analysis of the sample.

(C) Systems that recycle filter backwashwater must collect source water samples prior

to the point of filter backwash water addition. (D) Bank Filtration Requirements.

1. Systems that receive Cryptosporidiumtreatment credit for bank filtration under 10CSR 60-4.050(2)(F) as applicable, must col-lect source water samples in the surface waterprior to bank filtration.

2. Systems that use bank filtration aspretreatment to a filtration plant must collectsource water samples from the well (i.e.,after bank filtration). Use of bank filtrationduring monitoring must be consistent withroutine operational practice. Systems collect-ing samples after a bank filtration processmay not receive treatment credit for the bankfiltration under subsection (15)(C) of thisrule.

(E) Multiple Sources. Systems with plantsthat use multiple water sources, includingmultiple surface water sources and blendedsurface water and ground water sources, mustcollect samples as specified in paragraph(4)(E)1. or 2. of this rule. The use of multi-ple sources during monitoring must be con-sistent with routine operational practice.

1. If a sampling tap is available wherethe sources are combined prior to treatment,systems must collect samples from the tap.

2. If a sampling tap where the sourcesare combined prior to treatment is not avail-able, systems must collect samples at eachsource near the intake on the same day andmust follow either subparagraph (4)(E)2.A.or B. of this rule for sample analysis.

A. Systems may take composite sam-ples from each source into one (1) sampleprior to analysis. The volume of sample fromeach source must be weighted according tothe proportion of the source in the total plantflow at the time the sample is collected.

B. Systems may analyze samples fromeach source separately and calculate aweighted average of the analysis results foreach sampling date. The weighted averagemust be calculated by multiplying the analy-sis result for each source by the fraction thesource contributed to total plant flow at thetime the sample was collected and then sum-ming these values.

(F) Additional Requirements. Systems mustsubmit a description of their sampling loca-tion(s) to the department at the same time asthe sampling schedule required under section(3) of this rule. This description must addressthe position of the sampling location in rela-tion to the system’s water source(s) and treat-ment processes, including pretreatment, pointsof chemical treatment, and filter backwashrecycle. If the department does not respond toa system regarding sampling location(s), thesystem must sample at the reportedlocation(s).

(5) Approved Laboratories. (A) Cryptosporidium. Systems must have

Cryptosporidium samples analyzed by a labo-ratory that is approved under the EPA’sLaboratory Quality Assurance EvaluationProgram for Analysis of Cryptosporidium inWater or a laboratory that has been certifiedfor Cryptosporidium analysis by an equivalentstate laboratory certification program.

(B) E. Coli. Any laboratory certified by theEPA, the National Environmental LaboratoryAccreditation Conference, or the departmentfor total coliform or fecal coliform analysisunder 10 CSR 60-5.010(3) is approved for E.coli analysis under this rule when the labora-tory uses the same technique for E. coli thatthe laboratory uses for 10 CSR 60-5.010(3).

(C) Turbidity. Measurements of turbiditymust be made by a party approved by thedepartment.

(6) Reporting Source Water MonitoringResults.

(A) Systems must report results from thesource water monitoring required under sec-tion (2) of this rule no later than ten (10) daysafter the end of the first month following themonth when the sample is collected.

(B) All systems serving at least ten thou-sand (10,000) people must report the resultsfrom the initial source water monitoringrequired under subsection (2)(A) of this ruleto the EPA electronically at the web addressspecified by the EPA for this purpose. If asystem is unable to report monitoring resultselectronically, the system may use an alterna-tive approach for reporting monitoring resultsthat the EPA approves.

(C) Systems serving fewer than ten thou-sand (10,000) people must report results fromthe initial source water monitoring requiredunder subsection (2)(A) of this rule to thedepartment.

(D) All systems must report results fromthe second round of source water monitoringrequired under subsection (2)(B) of this ruleto the department.

(E) Systems must report the followingapplicable information for the source watermonitoring required under section (2) of thisrule:

1. For each Cryptosporidium analysis— A. Systems must report the following

data elements: (I) Public water system (PWS) ID; (II) Facility ID; (III) Sample collection date; (IV) Sample type (field or matrix

spike); (V) Sample volume filtered (L), to

nearest; (VI) Was one hundred percent



(100%) of filtered volume examined; and (VII) Number of oocysts counted;

B. For matrix spike samples, systemsmust also report the sample volume spikedand estimated number of oocysts spiked.These data are not required for field samples;

C. For samples in which less than ten(10) L is filtered or less than one hundredpercent (100%) of the sample volume isexamined, systems must also report the num-ber of filters used and the packed pellet vol-ume; and

D. For samples in which less than onehundred percent (100%) of sample volume isexamined, systems must also report the vol-ume of resuspended concentrate and volumeof this resuspension processed throughimmunomagnetic separation; and

2. For each E. coli analysis, systemsmust report the following data elements:

A. PWS ID; B. Facility ID; C. Sample collection date; D. Analytical method number;E. Method type; F. Source type (flowing stream,

lake/reservoir, GWUDISW); G. E. coli/100 mL; and H. Turbidity. (Systems serving fewer

than ten thousand (10,000) people that are notrequired to monitor for turbidity under sec-tion (2) of this rule are not required to reportturbidity with their E. coli results.)

(7) Grandfathering Previously CollectedData.

(A) Systems may use previously collecteddata to comply with the initial source watermonitoring requirements of subsection (2)(A)by grandfathering sample results that werecollected before the system is required tobegin monitoring. To be grandfathered, thesample results and analysis must meet the cri-teria in this section and must be approved bythe department. A filtered system may grand-father Cryptosporidium samples to meet therequirements of subsection (2)(A) when thesystem does not have corresponding E. coliand turbidity samples. A system that grandfa-thers Cryptosporidium samples without E.coli and turbidity samples is not required tocollect E. coli and turbidity samples when thesystem completes the requirements forCryptosporidium monitoring under subsec-tion (2)(A).

(B) E. Coli Sample Analysis. The analysisof E. coli samples must meet the analyticalmethod and approved laboratory require-ments of 10 CSR 60-5.010(3) and section (5)of this rule.

(C) Cryptosporidium Sample Analysis.The analysis of Cryptosporidium samples

must meet the criteria in this subsection. 1. Laboratories must have analyzed

Cryptosporidium samples using one (1) ofthese analytical methods:

A. Method 1623: Cryptosporidiumand Giardia in Water by Filtration/IMS/FA,2005, United States Environmental Protec-tion Agency, EPA–815–R–05–002;

B. Method 1622: Cryptosporidium inWater by Filtration/IMS/FA, 2005, UnitedStates Environmental Protection Agency,EPA–815–R–05–001;

C. Method 1623: Cryptosporidiumand Giardia in Water by Filtration/IMS/FA,2001, United States Environmental Protec-tion Agency, EPA–821–R–01–025;

D. Method 1622: Cryptosporidium inWater by Filtration/IMS/FA, 2001, UnitedStates Environmental Protection Agency,EPA–821–R–01–026;

E. Method 1623: Cryptosporidiumand Giardia in Water by Filtration/IMS/FA,1999, United States Environmental Protec-tion Agency, EPA–821–R–99–006; and

F. Method 1622: Cryptosporidium inWater by Filtration/IMS/FA, 1999, UnitedStates Environmental Protection Agency,EPA–821–R–99–001.

2. For each Cryptosporidium sample,the laboratory analyzed at least ten (10) L ofsample or at least two (2) mL of packed pel-let or as much volume as could be filtered bytwo (2) filters that EPA approved for themethods listed in paragraph (7)(C)1.

(D) Sampling Location. The samplinglocation must meet the conditions in section(4) of this rule.

(E) Sampling Frequency. Cryptosporidiumsamples were collected no less frequentlythan each calendar month on a regular sched-ule, beginning no earlier than January 1999.Sample collection intervals may vary for theconditions specified in paragraphs (3)(B)1.and 2. of this rule if the system provides doc-umentation of the condition when reportingmonitoring results.

1. The department may approve grandfa-thering of previously collected data wherethere are time gaps in the sampling frequen-cy if the system conducts additional monitor-ing the department specifies to ensure that thedata used to comply with the initial sourcewater monitoring requirements of subsection(2)(A) of this rule are seasonally representa-tive and unbiased.

2. Systems may grandfather previouslycollected data where the sampling frequencyvaried within each month. If theCryptosporidium sampling frequency varied,systems must follow the monthly averagingprocedure in paragraph (10)(B)5. of this rule,as applicable, when calculating the bin clas-

sification for filtered systems.(F) Reporting Monitoring Results for

Grandfathering. Systems that request tograndfather previously collected monitoringresults must report the following informationby the applicable dates listed in this subsec-tion. Systems serving at least ten thousand(10,000) people must report this informationto the EPA unless the department approvesreporting to the department rather than theEPA. Systems serving fewer than ten thou-sand (10,000) people must report this infor-mation to the department.

1. Systems must report that they intendto submit previously collected monitoringresults for grandfathering. This report mustspecify the number of previously collectedresults the system will submit, the dates ofthe first and last sample, and whether a sys-tem will conduct additional source watermonitoring to meet the requirements of sub-section (2)(A) of this rule. Systems mustreport this information no later than the datethe sampling schedule under section (3) ofthis rule is required.

2. Systems must report previously col-lected monitoring results for grandfathering,along with the associated documentation list-ed in the following subparagraphs no laterthan two (2) months after the applicable datelisted in subsection (2)(C) of this rule:

A. For each sample result, systemsmust report the applicable data elements insection (6) of this rule;

B. Systems must certify that thereported monitoring results include all resultsthe system generated during the time periodbeginning with the first reported result andending with the final reported result. Thisapplies to samples that were collected fromthe sampling location specified for sourcewater monitoring under this rule, not spiked,and analyzed using the laboratory’s routineprocess for the analytical methods listed inthis section;

C. Systems must certify that the sam-ples were representative of a plant’s sourcewater(s) and the source water(s) have notchanged. Systems must report a descriptionof the sampling location(s), which mustaddress the position of the sampling locationin relation to the system’s water source(s) andtreatment processes, including points ofchemical addition and filter backwash recy-cle; and

D. For Cryptosporidium samples, thelaboratory or laboratories that analyzed thesamples must provide a letter certifying thatthe quality control criteria specified in themethods listed in paragraph (7)(C)1. weremet for each sample batch associated with thereported results. Alternatively, the laboratory


Secretary of State


may provide bench sheets and sample exam-ination report forms for each field, matrixspike, Initial Precision and Recovery (IPR),Ongoing Precision and Recovery (OPR), andmethod blank sample associated with thereported results.

(G) If the department determines that apreviously collected data set submitted forgrandfathering was generated during sourcewater conditions that were not normal for thesystem, such as a drought, the departmentmay disapprove the data. Alternatively, thedepartment may approve the previously col-lected data if the system reports additionalsource water monitoring data, as determinedby the department, to ensure that the data setused under section (10) of this rule representsaverage source water conditions for the sys-tem.

(H) If a system submits previously collect-ed data that fully meet the number of samplesrequired for initial source water monitoringunder subsection (2)(A) of this rule and someof the data are rejected due to not meeting therequirements of this section, systems mustconduct additional monitoring to replacerejected data on a schedule the departmentapproves. Systems are not required to beginthis additional monitoring until two (2)months after notification that data have beenrejected and additional monitoring is neces-sary.

(8) Disinfection Profiling and BenchmarkingRequirements.

(A) Following the completion of initialsource water monitoring, a system that plansto make a significant change to its disinfec-tion practice, as defined in this section, mustdevelop disinfection profiles and calculatedisinfection benchmarks for Giardia lambliaand viruses as described in section (9) of thisrule. Prior to changing the disinfection prac-tice, the system must notify the departmentand must include in this notice the followinginformation:

1. A completed disinfection profile anddisinfection benchmark for Giardia lambliaand viruses as described in section (9) of thisrule;

2. A description of the proposed changein disinfection practice; and

3. An analysis of how the proposedchange will affect the current level of disin-fection.

(B) Significant changes to disinfectionpractice are defined as follows:

1. Changes to the point of disinfection; 2. Changes to the disinfectant(s) used in

the treatment plant; 3. Changes to the disinfection process;

or

4. Any other modification identified bythe department as a significant change to dis-infection practice.

(9) Developing the Disinfection Profile andBenchmark.

(A) Systems required to develop disinfec-tion profiles under section (8) of this rulemust follow the requirements of this section.Systems must monitor at least weekly for aperiod of twelve (12) consecutive months todetermine the total log inactivation forGiardia lamblia and viruses. If systems mon-itor more frequently, the monitoring frequen-cy must be evenly spaced. Systems that oper-ate for fewer than twelve (12) months peryear must monitor weekly during the periodof operation. Systems must determine loginactivation for Giardia lamblia through theentire plant, based on CT99.9 values in theGuidance Manual for Surface Water SystemTreatment Requirements, January 1992, asapplicable. Systems must determine log inac-tivation for viruses through the entire treat-ment plant based on a protocol approved bythe department.

(B) Systems with a single point of disin-fectant application prior to the entrance to thedistribution system must conduct the moni-toring specified here. Systems with more thanone (1) point of disinfectant application mustconduct this monitoring for each disinfectionsegment. Systems must monitor the parame-ters necessary to determine the total inactiva-tion ratio, using analytical methods in 10CSR 60- 5.010.

1. For systems using a disinfectant otherthan ultraviolet light (UV), the temperature ofthe disinfected water must be measured ateach residual disinfectant concentration sam-pling point during peak hourly flow or at analternative location approved by the depart-ment.

2. For systems using chlorine, the pH ofthe disinfected water must be measured ateach chlorine residual disinfectant concentra-tion sampling point during peak hourly flowor at an alternative location approved by thedepartment.

3. The disinfectant contact time(s), (t),must be determined during peak hourly flow.

4. The residual disinfectant concentra-tion(s), (C), of the water before or at the firstcustomer and prior to each additional point ofdisinfectant application must be measuredduring peak hourly flow.

(C) In lieu of conducting new monitoringunder subsection (9)(B), systems may elect tomeet the requirements of paragraph (9)(C)1.or 2.

1. Systems that have at least one (1) yearof existing data that are substantially equiva-

lent to data collected under the provisions ofsubsection (9)(B) may use these data to devel-op disinfection profiles as specified in thissection if the system has neither made a sig-nificant change to its treatment practice norchanged sources since the data were collect-ed. Systems may develop disinfection profilesusing up to three (3) years of existing data.

2. Systems may use disinfection pro-file(s) developed under 10 CSR 60-4.055(6)(C) in lieu of developing a new pro-file if the system has neither made a signifi-cant change to its treatment practice norchanged sources since the profile was devel-oped. Systems that have not developed avirus profile under 10 CSR 60-4.055(6)(C)must develop a virus profile using the samemonitoring data on which the Giardia lam-blia profile is based.

(D) Systems must calculate the total inacti-vation ratio for Giardia lamblia as specifiedhere.

1. Systems using only one (1) point ofdisinfectant application may determine thetotal inactivation ratio for the disinfectionsegment based on either of the methods insubparagraph (9)(D)1.A. or B.

A. Determine one (1) inactivationratio (CTcalc/CT99.9) before or at the firstcustomer during peak hourly flow.

B. Determine successive CTcalc/CT99.9 values, representing sequential inacti-vation ratios, between the point of disinfec-tant application and a point before or at thefirst customer during peak hourly flow. Thesystem must calculate the total inactivationratio by determining (CTcalc/CT99.9) for eachsequence and then adding the (CTcalc/CT99.9) values together to determine ((CTcalc/CT99.9)).

2. Systems using more than one (1)point of disinfectant application before thefirst customer must determine the CT valueof each disinfection segment immediatelyprior to the next point of disinfectant applica-tion, or for the final segment, before or at thefirst customer, during peak hourly flow. The(CTcalc/CT99.9) value of each segment and ((CTcalc/CT99.9)) must be calculated using themethod in subparagraph (9)(D)1.A. of thissection.

3. The system must determine the totallogs of inactivation by multiplying the valuecalculated in paragraph (9)(D)1. or 2. bythree (3).

4. Systems must calculate the log ofinactivation for viruses using a protocolapproved by the department.

(E) Systems must use the procedures spec-ified in paragraphs (9)(E)1. and 2. to calcu-late a disinfection benchmark.



1. For each year of profiling data col-lected and calculated under subsections(9)(A)–(D) of this rule, systems must deter-mine the lowest mean monthly level of bothGiardia lamblia and virus inactivation.Systems must determine the mean Giardialamblia and virus inactivation for each calen-dar month for each year of profiling data bydividing the sum of daily or weekly Giardialamblia and virus log inactivation by thenumber of values calculated for that month.

2. The disinfection benchmark is thelowest monthly mean value (for systems withone (1) year of profiling data) or the mean ofthe lowest monthly mean values (for systemswith more than one (1) year of profiling data)of Giardia lamblia and virus log inactivationin each year of profiling data.

(10) Bin Classification for Filtered Systems. (A) Following completion of the initial

round of source water monitoring requiredunder subsection (2)(A) of this rule, filteredsystems must calculate an initialCryptosporidium bin concentration for eachplant for which monitoring was required.Calculation of the bin concentration must usethe Cryptosporidium results reported undersubsection (2)(A) of this rule and must followthe procedures in subsection (10)(B) of thisrule.

(B) Procedures for Bin Determination.1. For systems that collect a total of at

least forty-eight (48) samples, the bin con-centration is equal to the arithmetic mean ofall sample concentrations.

2. For systems that collect a total of atleast twenty-four (24) samples, but not morethan forty-seven (47) samples, the bin con-centration is equal to the highest arithmeticmean of all sample concentrations in anytwelve (12) consecutive months during whichCryptosporidium samples were collected.

3. For systems that serve fewer than tenthousand (10,000) people and monitor forCryptosporidium for only one (1) year (thatis, collect twenty-four (24) samples in twelve(12) months), the bin concentration is equalto the arithmetic mean of all sample concen-trations.

4. For systems with plants operatingonly part of the year that monitor fewer thantwelve (12) months per year under subsection(2)(E) of this rule, the bin concentration isequal to the highest arithmetic mean of allsample concentrations during any year ofCryptosporidium monitoring.

5. If the monthly Cryptosporidium sam-pling frequency varies, systems must first cal-culate a monthly average for each month ofmonitoring. Systems must then use thesemonthly average concentrations, rather than

individual sample concentrations, in theapplicable calculation for bin classification inparagraphs (10)(B)1.–5. of this rule.

(C) Filtered systems must determine theirinitial bin classification from the followingtable and using the Cryptosporidium bin con-centration calculated under subsections(10)(A) and (B).


Secretary of State


(D) Following completion of the secondround of source water monitoring requiredunder subsection (2)(B), filtered systemsmust recalculate their Cryptosporidium binconcentration using the Cryptosporidiumresults reported under subsection (2)(B) andfollowing the procedures in paragraphs(10)(B)1. through 4. Systems must then rede-termine their bin classification using this binconcentration and the table in subsection(10)(C) of this rule.

(E) Reporting Bin Classification Require-ments.

1. Filtered systems must report their ini-tial bin classification under subsection(10)(C) to the department for approval nolater than six (6) months after the system isrequired to complete initial source watermonitoring based on the schedule in subsec-tion (2)(C) of this rule.

2. Systems must report their bin classi-fication under subsection (10)(D) to thedepartment for approval no later than six (6)months after the system is required to com-plete the second round of source water mon-itoring based on the schedule in subsection(2)(C) of this rule.

3. The bin classification report to thedepartment must include a summary ofsource water monitoring data and the calcula-tion procedure used to determine bin classifi-cation.

(F) Failure to comply with the conditionsof subsection (10)(E) of this rule is a violationof the treatment technique requirement.

(11) Additional Cryptosporidium TreatmentRequirements.

(A) Filtered systems must provide the levelof additional treatment for Cryptosporidiumspecified in this subsection based on their binclassification as determined under section(10) of this rule and according to the schedulein section (12) of this rule.



For systems that are: With a Cryptosporidium bin concentration (based on calculations in subsection (10)(A) or (10)(B) as applicable) of:

The bin classification is:

Required to monitor for Cryptosporidium under section (2) of this rule.

Cryptosporidium < 0.075 oocyst/L Bin 1 0.075 oocysts/L Cryptosporidium < 1.0 oocysts/L

Bin 2

1.0 oocysts/L Cryptosporidium < 3.0 oocysts/L

Bin 3

Cryptosporidium 3.0 oocysts/L Bin 4 Serving fewer than 10,000 people and NOT required to monitor for Cryptosporidium under paragraph (2)(A)3.

NA

Bin 1

Bin Classification Table for Filtered Systems

(B) Filtered systems must use one (1) ormore of the treatment and managementoptions listed in section (13) of this rule,termed the Microbial Toolbox, to complywith the additional Cryptosporidium treat-ment required in subsection (11)(A) of thisrule.

1. Systems classified in Bin 3 and Bin 4must achieve at least 1-log of the additionalCryptosporidium treatment required undersubsection (11)(A) of this rule using eitherone (1) or a combination of the following:bag filters, bank filtration, cartridge filters,chlorine dioxide, membranes, ozone, or UV,as described in sections (14) through (18) ofthis rule.

(C) Failure by a system in any month toachieve treatment credit by meeting criteria insections (14) through (18) of this rule formicrobial toolbox options that is at leastequal to the level of treatment required insubsection (11)(A) of this rule is a violation ofthe treatment technique requirement.

(D) If the department determines during asanitary survey or an equivalent source waterassessment that, after a system completed the

monitoring conducted under subsection(2)(A) or (2)(B) of this rule, significantchanges occurred in the system’s watershedthat could lead to increased contamination ofthe source water by Cryptosporidium, the sys-tem must take actions specified by the depart-ment to address the contamination. Theseactions may include additional source watermonitoring and/or implementing microbialtoolbox options listed in section (13) of thisrule.

(12) Schedule for Compliance WithCryptosporidium Treatment Requirements.

(A) Following initial bin classificationunder subsection (10)(C), filtered systemsmust provide the level of treatment forCryptosporidium required under section (11)according to the following Cryptosporidiumtreatment compliance dates.


Secretary of State


If the system bin classification is:

And the system uses the following filtration treatment in full compliance with 10 CSR 60-4.050, 10 CSR 60-4.055, and 10 CSR 60-7.010 (as applicable), then the additional Cryptosporidium treatment requirements are: Conventional filtration treatment (including softening)

Direct Filtration Slow sand or diatomaceous earth filtration

Alternative filtration technologies

Bin 1 No additional treatment

No additional treatment



Bin 2 1-log treatment 1.5-log treatment 1-log treatment As determined by the department such that the total Cryptosporidium removal and inactivation is at least 4.0-log.

Bin 3 2-log treatment 2.5-log treatment 2-log treatment As determined by the department such that the total Cryptosporidium removal and inactivation is at least 5.0-log.

Bin 4 2.5-log treatment 3-log treatment 2.5-log treatment As determined by the department such that the total Cryptosporidium removal and inactivation is at least 5.5-log.

(B) If the bin classification for a filteredsystem changes following the second round ofsource water monitoring, as determinedunder subsection (10)(D) of this rule, the sys-tem must provide the level of treatment forCryptosporidium required under section (11)of this rule on a schedule the departmentapproves.

(13) Microbial Toolbox Options for MeetingCryptosporidium Treatment Requirements.

(A) Systems receive the treatment creditlisted in the table in subsection (13)(B) of thisrule by meeting the conditions for microbialtoolbox options described in sections (14)through (18) of this rule. Systems apply thesetreatment credits to meet the treatmentrequirements in section (11) of this rule, asapplicable.

(B) The following table summarizesoptions in the microbial toolbox:



Cryptosporidium Treatment Compliance Dates Table

Systems that serve:

Must comply with Cryptosporidium treatment requirements no later than the following dates, except that the department may allow up to an additional two (2) years for complying with the treatment requirement for systems making capital improvements:

1. At least 100,000 people April 1, 2012

2. From 50,000 to 99,999 people October 1, 2012 3. From 10,000 to 49,999 people October 1, 2013

4. Fewer than 10,000 people October 1, 2014


Secretary of State




(14) Source Toolbox Components. (A) Watershed Control Program. Systems

receive 0.5-log Cryptosporidium treatmentcredit for implementing a watershed controlprogram that meets the requirements of thissection.

1. Systems that intend to apply for thewatershed control program credit must notifythe department of this intent no later than two(2) years prior to the treatment compliancedate applicable to the system in section (12)of this rule.

2. Systems must submit to the depart-ment a proposed watershed control plan nolater than one (1) year before the applicabletreatment compliance date in section (12) ofthis rule. The department must approve thewatershed control plan for the system toreceive watershed control program treatmentcredit. The watershed control plan mustinclude the elements in subparagraphs(14)(A)2.A.–D. of this rule.

A. Identification of an “area of influ-ence” outside of which the likelihood ofCryptosporidium or fecal contaminationaffecting the treatment plant intake is not sig-nificant. This is the area to be evaluated infuture watershed surveys under subparagraph(14)(A)5.B.

B. Identification of both potential andactual sources of Cryptosporidium contami-nation and an assessment of the relativeimpact of these sources on the system’ssource water quality.

C. An analysis of the effectivenessand feasibility of control measures that couldreduce Cryptosporidium loading fromsources of contamination to the system’ssource water.

D. A statement of goals and specificactions the system will undertake to reducesource water Cryptosporidium levels. Theplan must explain how the actions are expect-ed to contribute to specific goals, identifywatershed partners and their roles, identifyresource requirements and commitments, andinclude a schedule for plan implementationwith deadlines for completing specific actionsidentified in the plan.

3. Systems with existing watershed con-trol programs (that is, programs in place onJanuary 5, 2006) are eligible to seek thiscredit. Their watershed control plans mustmeet the criteria in paragraph (14)(A)2. ofthis rule and must specify ongoing and futureactions that will reduce source waterCryptosporidium levels.

4. If the department does not respond toa system regarding approval of a watershedcontrol plan submitted under this section andthe system meets the other requirements ofthis section, the watershed control program

will be considered approved and 0.5-logCryptosporidium treatment credit will beawarded unless and until the department sub-sequently withdraws such approval.

5. Systems must complete the actions insubparagraphs (14)(A)5.A.–C. of this rule tomaintain the 0.5-log credit.

A. Submit an annual watershed con-trol program status report to the department.The annual watershed control program statusreport must describe the system’s implemen-tation of the approved plan and assess theadequacy of the plan to meet its goals. It mustexplain how the system is addressing anyshortcomings in plan implementation, includ-ing those previously identified by the depart-ment or as the result of the watershed surveyconducted under subparagraph (14)(A)5.B. ofthis rule. It must also describe any significantchanges that have occurred in the watershedsince the last watershed sanitary survey. If asystem determines during implementationthat making a significant change to itsapproved watershed control program is nec-essary, the system must notify the departmentprior to making any such changes. If anychange is likely to reduce the level of sourcewater protection, the system must also list inits notification the actions the system willtake to mitigate this effect.

B. Undergo a watershed sanitary sur-vey every three (3) years for communitywater systems and every five (5) years fornoncommunity water systems and submit thesurvey report to the department. The surveymust be conducted according to departmentguidelines and by persons the departmentapproves.

(I) The watershed sanitary surveymust meet the following criteria: encompassthe region identified in the department-approved watershed control plan as the areaof influence; assess the implementation ofactions to reduce source waterCryptosporidium levels; and identify any sig-nificant new sources of Cryptosporidium.

(II) If the department determinesthat significant changes may have occurred inthe watershed since the previous watershedsanitary survey, systems must undergo anoth-er watershed sanitary survey by a date thedepartment requires, which may be earlierthan the regular date in subparagraph(14)(A)5.B. of this rule.

C. The system must make the water-shed control plan, annual status reports, andwatershed sanitary survey reports available tothe public upon request. These documentsmust be in a plain language style and includecriteria by which to evaluate the success ofthe program in achieving plan goals. Thedepartment may approve systems to withhold

from the public portions of the annual statusreport, watershed control plan, and watershedsanitary survey based on water supply securi-ty considerations.

6. If the department determines that asystem is not carrying out the approvedwatershed control plan, the department maywithdraw the watershed control programtreatment credit.

(B) Alternative Source Requirements. 1. A system may conduct source water

monitoring that reflects a different intakelocation (either in the same source or for analternate source) or a different procedure forthe timing or level of withdrawal from thesource (alternative source monitoring). If thedepartment approves, a system may deter-mine its bin classification under section (10)of this rule based on the alternative sourcemonitoring results.

2. If systems conduct alternative sourcemonitoring under paragraph (14)(B)1. of thisrule, systems must also monitor their currentplant intake concurrently as described in sec-tion (2) of this rule.

3. Alternative source monitoring underparagraph (14)(B)1. of this rule must meetthe requirements for source monitoring todetermine bin classification, as described insections (2)–(6) of this rule. Systems mustreport the alternative source monitoringresults to the department, along with sup-porting information documenting the operat-ing conditions under which the samples werecollected.

4. If a system determines its bin classi-fication under section (10) of this rule usingalternative source monitoring results thatreflect a different intake location or a differ-ent procedure for managing the timing orlevel of withdrawal from the source, the sys-tem must relocate the intake or permanentlyadopt the withdrawal procedure, as applica-ble, no later than the applicable treatmentcompliance date in section (12) of this rule.

(15) Pre-Filtration Treatment Toolbox Com-ponents.

(A) Presedimentation. Systems receive0.5-log Cryptosporidium treatment credit fora presedimentation basin during any monththe process meets the criteria in this subsec-tion.

1. The presedimentation basin must bein continuous operation and must treat theentire plant flow taken from a surface wateror GWUDISW source.

2. The system must continuously add acoagulant to the presedimentation basin.

3. The presedimentation basin mustachieve the performance criteria in subpara-graph (15)(A)3.A. or B. of this rule.


Secretary of State


A. Demonstrates at least 0.5-logmean reduction of influent turbidity. Thisreduction must be determined using daily tur-bidity measurements in the presedimentationprocess influent and effluent and must be cal-culated as follows: log10(monthly mean ofdaily influent turbidity) − log10(monthlymean of daily effluent turbidity).

B. Complies with department-approved performance criteria that demon-strate at least 0.5-log mean removal ofmicron-sized particulate material through thepresedimentation process.

(B) Two (2)-Stage Lime Softening.Systems receive an additional 0.5-logCryptosporidium treatment credit for a two(2)-stage lime softening plant if chemicaladdition and hardness precipitation occur intwo (2) separate and sequential softeningstages prior to filtration. Both softeningstages must treat the entire plant flow takenfrom a surface water or GWUDISW source.

(C) Bank Filtration. Systems receiveCryptosporidium treatment credit for bankfiltration that serves as pretreatment to a fil-tration plant by meeting the criteria in thissubsection. Systems using bank filtrationwhen they begin source water monitoringunder subsection (2)(A) of this rule must col-lect samples as described in subsection(4)(D) of this rule and are not eligible for thiscredit.

1. Wells with a ground water flow pathof at least twenty-five feet (25') receive 0.5-log treatment credit; wells with a groundwater flow path of at least fifty feet (50')receive 1.0-log treatment credit. The groundwater flow path must be determined as spec-ified in paragraph (15)(C)4. of this rule.

2. Only wells in granular aquifers areeligible for treatment credit. Granularaquifers are those comprised of sand, clay,silt, rock fragments, pebbles or larger parti-cles, and minor cement. A system must char-acterize the aquifer at the well site to deter-mine aquifer properties. Systems must extracta core from the aquifer and demonstrate that,in at least ninety percent (90%) of the corelength, grains less than 1.0 mm in diameterconstitute at least ten percent (10%) of thecore material.

3. Only horizontal and vertical wells areeligible for treatment credit.

4. For vertical wells, the ground waterflow path is the measured distance from theedge of the surface water body under highflow conditions (determined by the one hun-dred (100)-year floodplain elevation boundaryor by the floodway, as defined in FederalEmergency Management Agency flood haz-ard maps) to the well screen. For horizontalwells, the ground water flow path is the mea-

sured distance from the bed of the river undernormal flow conditions to the closest hori-zontal well lateral screen.

5. Systems must monitor each wellheadfor turbidity at least once every four (4) hourswhile the bank filtration process is in opera-tion. If monthly average turbidity levels,based on daily maximum values in the well,exceed one (1) nephelometric turbidity unit(NTU), the system must report this result tothe department and conduct an assessmentwithin thirty (30) days to determine the causeof the high turbidity levels in the well. If thedepartment determines that microbialremoval has been compromised, the depart-ment may revoke treatment credit until thesystem implements corrective actionsapproved by the department to remediate theproblem.

6. Springs and infiltration galleries arenot eligible for treatment credit under thissection but are eligible for credit under sub-section (16)(C) of this rule.

7. Bank filtration demonstration of per-formance. The department may approveCryptosporidium treatment credit for bankfiltration based on a demonstration of perfor-mance study that meets the criteria in thissubsection. This treatment credit may begreater than 1.0-log and may be awarded tobank filtration that does not meet the criteriain paragraphs (15)(C)1.–5. of this rule.

A. The study must follow a depart-ment-approved protocol and must involve thecollection of data on the removal ofCryptosporidium or a surrogate forCryptosporidium and related hydrogeologicand water quality parameters during the fullrange of operating conditions.

B. The study must include samplingboth from the production well(s) and frommonitoring wells that are screened and locat-ed along the shortest flow path between thesurface water source and the productionwell(s).

(16) Treatment Performance Toolbox Compo-nents.

(A) Combined Filter Performance. Systemsusing conventional filtration treatment ordirect filtration treatment receive an addition-al 0.5-log Cryptosporidium treatment creditduring any month the system meets the crite-ria in this subsection. Combined filter effluent(CFE) turbidity must be less than or equal to0.15 NTU in at least ninety-five percent(95%) of the measurements. Turbidity must bemeasured as described in 10 CSR 60-4.050(2)and 10 CSR 60-4.080(3).

(B) Individual Filter Performance. Systemsusing conventional filtration treatment ordirect filtration treatment receive 0.5-log

Cryptosporidium treatment credit, which canbe in addition to the 0.5-log credit under sub-section (16)(A) during any month the systemmeets the criteria in this subsection.Compliance with these criteria must be basedon individual filter turbidity monitoring asdescribed in 10 CSR 60-4.050(2)(D) and 10CSR 60-7.010(6).

1. The filtered water turbidity for eachindividual filter must be less than or equal to0.15 NTU in at least ninety-five percent(95%) of the measurements recorded eachmonth.

2. No individual filter may have a mea-sured turbidity greater than 0.3 NTU in two(2) consecutive measurements taken fifteen(15) minutes apart.

3. Any system that has received treat-ment credit for individual filter performanceand fails to meet the requirements of para-graph (16)(B)1. or 2. of this rule during anymonth does not receive a treatment techniqueviolation under subsection (11)(C) of this ruleif the department determines the following:

A. The failure was due to unusual andshort-term circumstances that could not rea-sonably be prevented through optimizingtreatment plant design, operation, and main-tenance; and

B. The system has experienced nomore than two (2) such failures in any calen-dar year.

(C) Demonstration of Performance. Thedepartment may approve Cryptosporidiumtreatment credit for drinking water treatmentprocesses based on a demonstration of per-formance study that meets the criteria in thissubsection. This treatment credit may begreater than or less than the prescribed treat-ment credits in section (11) or section (15)through section (18) of this rule and may beawarded to treatment processes that do notmeet the criteria for the prescribed credits.

1. Systems cannot receive the prescribedtreatment credit for any toolbox option in sec-tions (15) through (18) if that toolbox optionis included in a demonstration of perfor-mance study for which treatment credit isawarded under this paragraph.

2. The demonstration of performancestudy must follow a department-approvedprotocol and must demonstrate the level ofCryptosporidium reduction the treatment pro-cess will achieve under the full range ofexpected operating conditions for the system.

3. Approval by the department must bein writing and may include monitoring andtreatment performance criteria that the sys-tem must demonstrate and report on an ongo-ing basis to remain eligible for the treatmentcredit. The department may designate suchcriteria, where necessary, to verify that the



conditions under which the demonstration ofperformance credit was approved are main-tained during routine operation.

(17) Additional Filtration Toolbox Compo-nents.

(A) Bag and Cartridge Filters. Systemsreceive Cryptosporidium treatment credit ofup to 2.0-log for individual bag or cartridgefilters and up to 2.5-log for bag or cartridgefilters operated in series by meeting the crite-ria in paragraphs (17)(A)1. through 10. ofthis section. To be eligible for this credit, sys-tems must report the results of challenge test-ing that meets the requirements of paragraphs(17)(A)2. through 9. to the department. Thefilters must treat the entire plant flow takenfrom a surface water or ground water underthe direct influence of surface water source.

1. The Cryptosporidium treatment cred-it awarded to bag or cartridge filters must bebased on the removal efficiency demonstratedduring challenge testing that is conductedaccording to the criteria in paragraphs(17)(A)2. through 9. A factor of safety equalto 1-log for individual bag or cartridge filtersand 0.5-log for bag or cartridge filters inseries must be applied to challenge testingresults to determine removal credit. Systemsmay use results from challenge testing con-ducted prior to January 5, 2006, if the priortesting was consistent with the criteria speci-fied in paragraphs (17)(A)2. through 9.

2. Challenge testing must be performedon full-scale bag or cartridge filters, and theassociated filter housing or pressure vessel,that are identical in material and constructionto the filters and housings the system will usefor removal of Cryptosporidium. Bag or car-tridge filters must be challenge tested in thesame configuration that the system will use,either as individual filters or as a series con-figuration of filters.

3. Challenge testing must be conductedusing Cryptosporidium or a surrogate that isremoved no more efficiently than Crypto-sporidium. The microorganism or surrogateused during challenge testing is referred to asthe challenge particulate. The concentrationof the challenge particulate must be deter-mined using a method capable of discretelyquantifying the specific microorganism orsurrogate used in the test; gross measure-ments such as turbidity may not be used.

4. The maximum feed water concentra-tion that can be used during a challenge testmust be based on the detection limit of thechallenge particulate in the filtrate (i.e., fil-trate detection limit) and must be calculatedusing the following equation:

Maximum Feed Concentration = 1 ×104 × (Filtrate Detection Limit).

5. Challenge testing must be conductedat the maximum design flow rate for the fil-ter as specified by the manufacturer.

6. Each filter evaluated must be testedfor a duration sufficient to reach one hundredpercent (100%) of the terminal pressure drop,which establishes the maximum pressuredrop under which the filter may be used tocomply with the requirements of this rule.

7. Removal efficiency of a filter must bedetermined from the results of the challengetest and expressed in terms of log removalvalues using the following equation:

LRV = LOG10(Cf) − LOG10(Cp)

Where: LRV = log removal value demonstrated

during challenge testingCf = the feed concentration measured dur-

ing the challenge testCp = the filtrate concentration measured

during the challenge test

In applying this equation, the same unitsmust be used for the feed and filtrate concen-trations. If the challenge particulate is notdetected in the filtrate, then the term Cp mustbe set equal to the detection limit.

8. Each filter tested must be challengedwith the challenge particulate during three (3)periods over the filtration cycle: within two(2) hours of start-up of a new filter; when thepressure drop is between forty-five percentand fifty-five percent (45%–55%) of the ter-minal pressure drop; and at the end of thecycle after the pressure drop has reached onehundred percent (100%) of the terminal pres-sure drop. An LRV must be calculated foreach of these challenge periods for each filtertested. The LRV for the filter (LRVfilter) mustbe assigned the value of the minimum LRVobserved during the three (3) challenge peri-ods for that filter.

9. If fewer than twenty (20) filters aretested, the overall removal efficiency for thefilter product line must be set equal to thelowest LRVfilter among the filters tested. Iftwenty (20) or more filters are tested, theoverall removal efficiency for the filter prod-uct line must be set equal to the 10th per-centile of the set of LRVfilter values for thevarious filters tested. The percentile isdefined by (i/(n+1)) where i is the rank of nindividual data points ordered lowest to high-est. If necessary, the 10th percentile may becalculated using linear interpolation.

10. If a previously tested filter is modi-fied in a manner that could change theremoval efficiency of the filter product line,challenge testing to demonstrate the removalefficiency of the modified filter must be con-

ducted and submitted to the department. (B) Membrane Filtration Requirements.

1. Systems receive Cryptosporidiumtreatment credit for membrane filtration thatmeets the criteria of this paragraph.Membrane cartridge filters that meet the def-inition of membrane filtration in 10 CSR 60-2.015 are eligible for this credit. The level oftreatment credit a system receives is equal tothe lower of the values determined under sub-paragraphs (17)(B)1.A. and B.

A. The removal efficiency demon-strated during challenge testing conductedunder the conditions in paragraph (17)(B)2.

B. The maximum removal efficiencythat can be verified through direct integritytesting used with the membrane filtration pro-cess under the conditions in paragraph(17)(B)3.

2. Challenge testing. The membraneused by the system must undergo challengetesting to evaluate removal efficiency, and thesystem must report the results of challengetesting to the department. Challenge testingmust be conducted according to the criteria insubparagraphs (17)(B)2.A. through H.Systems may use data from challenge testingconducted prior to January 5, 2006, if theprior testing was consistent with the criteriain subparagraphs (17)(B)2.A. through G.

A. Challenge testing must be con-ducted on either a full-scale membrane mod-ule, identical in material and construction tothe membrane modules used in the system’streatment facility, or a smaller-scale mem-brane module, identical in material and simi-lar in construction to the full-scale module.A module is defined as the smallest compo-nent of a membrane unit in which a specificmembrane surface area is housed in a devicewith a filtrate outlet structure.

B. Challenge testing must be conduct-ed using Cryptosporidium oocysts or a surro-gate that is removed no more efficiently thanCryptosporidium oocysts. The organism orsurrogate used during challenge testing isreferred to as the challenge particulate. Theconcentration of the challenge particulate, inboth the feed and filtrate water, must bedetermined using a method capable of dis-cretely quantifying the specific challenge par-ticulate used in the test; gross measurementssuch as turbidity may not be used.

C. The maximum feed water concen-tration that can be used during a challengetest is based on the detection limit of the chal-lenge particulate in the filtrate and must bedetermined according to the following equa-tion:

Maximum Feed Concentration = 3.16 ×106 × (Filtrate Detection Limit)

D. Challenge testing must be con-ducted under representative hydraulic condi-tions at the maximum design flux and maxi-mum design process recovery specified by themanufacturer for the membrane module.Flux is defined as the throughput of a pres-sure-driven membrane process expressed asflow per unit of membrane area. Recovery isdefined as the volumetric percent of feedwater that is converted to filtrate over thecourse of an operating cycle uninterrupted byevents such as chemical cleaning or a solidsremoval process (i.e., backwashing).

E. Removal efficiency of a membranemodule must be calculated from the challengetest results and expressed as a log removalvalue according to the following equation:

LRV = LOG10(Cf) − LOG10(Cp) Where: LRV = log removal value demonstrated

during the challenge testCf = the feed concentration measured dur-

ing the challenge testCp = the filtrate concentration measured

during the challenge test

Equivalent units must be used for the feedand filtrate concentrations. If the challengeparticulate is not detected in the filtrate, theterm Cp is set equal to the detection limit forthe purpose of calculating the LRV. An LRVmust be calculated for each membrane mod-ule evaluated during the challenge test.

F. The removal efficiency of a mem-brane filtration process demonstrated duringchallenge testing must be expressed as a logremoval value (LRVC-Test). If fewer than twen-ty (20) modules are tested, then LRVC-Test isequal to the lowest of the representative LRVsamong the modules tested. If twenty (20) ormore modules are tested, then LRVC-Test isequal to the 10th percentile of the representa-tive LRVs among the modules tested. Thepercentile is defined by (i/(n+1)) where i isthe rank of n individual data points orderedlowest to highest. If necessary, the 10th per-centile may be calculated using linear inter-polation.

G. The challenge test must establish aquality control release value (QCRV) for anon-destructive performance test that demon-strates the Cryptosporidium removal capabil-ity of the membrane filtration module. Thisperformance test must be applied to each pro-duction membrane module used by the sys-tem that was not directly challenge tested inorder to verify Cryptosporidium removalcapability. Production modules that do notmeet the established QCRV are not eligiblefor the treatment credit demonstrated duringthe challenge test.

H. If a previously tested membrane ismodified in a manner that could change theremoval efficiency of the membrane or theapplicability of the non-destructive perfor-mance test and associated QCRV, additionalchallenge testing to demonstrate the removalefficiency of, and determine a new QCRVfor, the modified membrane must be con-ducted and submitted to the department.

3. Direct integrity testing. Systemsmust conduct direct integrity testing in amanner that demonstrates a removal efficien-cy equal to or greater than the removal cred-it awarded to the membrane filtration processand meets the requirements described in sub-paragraphs (17)(B)3.A.–G. of this rule. Adirect integrity test is defined as a physicaltest applied to a membrane unit in order toidentify and isolate integrity breaches (that is,one (1) or more leaks that could result in con-tamination of the filtrate).

A. The direct integrity test must beindependently applied to each membrane unitin service. A membrane unit is defined as agroup of membrane modules that share com-mon valving that allows the unit to be isolat-ed from the rest of the system for the purposeof integrity testing or other maintenance.

B. The direct integrity method musthave a resolution of three (3) micrometers orless, where resolution is defined as the size ofthe smallest integrity breach that contributesto a response from the direct integrity test.

C. The direct integrity test must havea sensitivity sufficient to verify the log treat-ment credit awarded to the membrane filtra-tion process by the department, where sensi-tivity is defined as the maximum log removalvalue that can be reliably verified by a directintegrity test. Sensitivity must be determinedusing the approach in either part(17)(B)3.C.(I) or (II) of this section as appli-cable to the type of direct integrity test thesystem uses.

(I) For direct integrity tests that usean applied pressure or vacuum, the directintegrity test sensitivity must be calculatedaccording to the following equation:

LRVDIT = LOG10 (Qp /(VCF × Qbreach))

Where: LRVDIT = the sensitivity of the direct

integrity testQp = total design filtrate flow from the

membrane unitQbreach = flow of water from an integrity

breach associated with the small-est integrity test response thatcan be reliably measured

VCF = volumetric concentration factor

The volumetric concentration factor is the

ratio of the suspended solids concentration onthe high pressure side of the membrane rela-tive to that in the feed water.

(II) For direct integrity tests thatuse a particulate or molecular marker, thedirect integrity test sensitivity must be calcu-lated according to the following equation:

LRVDIT = LOG10(Cf) − LOG10(Cp)

Where: LRVDIT = the sensitivity of the direct

integrity testCf = the typical feed concentration of the

marker used in the testCp = the filtrate concentration of the

marker from an integral membraneunit

D. Systems must establish a controllimit within the sensitivity limits of the directintegrity test that is indicative of an integralmembrane unit capable of meeting theremoval credit awarded by the department.

E. If the result of a direct integritytest exceeds the control limit establishedunder subparagraph (17)(B)3.D., the systemmust remove the membrane unit from ser-vice. Systems must conduct a direct integritytest to verify any repairs and may return themembrane unit to service only if the directintegrity test is within the established controllimit.

F. Systems must conduct directintegrity testing on each membrane unit at afrequency of not less than once each day thatthe membrane unit is in operation. Thedepartment may approve less frequent testing,based on demonstrated process reliability, theuse of multiple barriers effective forCryptosporidium, or reliable process safe-guards.

4. Indirect integrity monitoring.Systems must conduct continuous indirectintegrity monitoring on each membrane unitaccording to the criteria in subparagraphs(17)(B)4.A. through E. Indirect integritymonitoring is defined as monitoring someaspect of filtrate water quality that is indica-tive of the removal of particulate matter. Asystem that implements continuous directintegrity testing of membrane units in accor-dance with the criteria in subparagraphs(17)(B)3.A. through E. of this section is notsubject to the requirements for continuousindirect integrity monitoring. Systems mustsubmit a monthly report to the departmentsummarizing all continuous indirect integritymonitoring results triggering direct integritytesting and the corrective action that wastaken in each case.

A. Unless the department approves analternative parameter, continuous indirect


Secretary of State


integrity monitoring must include continuousfiltrate turbidity monitoring.

B. Continuous monitoring must beconducted at a frequency of no less than onceevery fifteen (15) minutes.

C. Continuous monitoring must beseparately conducted on each membrane unit.

D. If indirect integrity monitoringincludes turbidity and if the filtrate turbidityreadings are above 0.15 NTU for a periodgreater than fifteen (15) minutes (i.e., two (2)consecutive fifteen (15)-minute readingsabove 0.15 NTU), direct integrity testingmust immediately be performed on the asso-ciated membrane unit as specified in sub-paragraphs (17)(B)3.A. through E.

E. If indirect integrity monitoringincludes a department-approved alternativeparameter and if the alternative parameterexceeds a department-approved control limitfor a period greater than fifteen (15) minutes,direct integrity testing must immediately beperformed on the associated membrane unitsas specified in subparagraphs (17)(B)3.A.through E.

(C) Second Stage Filtration. Systemsreceive 0.5-log Cryptosporidium treatmentcredit for a separate second stage of filtrationthat consists of sand, dual media, granularactivated carbon (GAC), or other fine grainmedia following granular media filtration ifthe department approves. To be eligible forthis credit, the first stage of filtration must bepreceded by a coagulation step, and both fil-tration stages must treat the entire plant flowtaken from a surface water or GWUDISWsource. A cap, such as GAC, on a singlestage of filtration is not eligible for this cred-it. The department must approve the treat-ment credit based on an assessment of thedesign characteristics of the filtration pro-cess.

(D) Slow Sand Filtration (as SecondaryFilter). Systems are eligible to receive 2.5-log Cryptosporidium treatment credit for aslow sand filtration process that follows a sep-arate stage of filtration if both filtration stagestreat entire plant flow taken from a surfacewater or GWUDISW source and no disinfec-tant residual is present in the influent water tothe slow sand filtration process. The depart-ment must approve the treatment credit basedon an assessment of the design characteristicsof the filtration process. This subsectiondoes not apply to treatment credit awarded toslow sand filtration used as a primary filtra-tion process.

(18) Inactivation Toolbox Components.(A) Calculation of CT Values.

1. CT is the product of the disinfectantcontact time (T, in minutes) and disinfectant

concentration (C, in milligrams per liter).Systems with treatment credit for chlorinedioxide or ozone under subsection (18)(B) or(C) must calculate CT at least once each day,with both C and T measured during peakhourly flow as specified in 10 CSR 60-5.010,10 CSR 60-5.020, and the Missouri GuidanceManual for Surface Water System TreatmentRequirements, 1992.

2. Systems with several disinfection seg-ments in sequence may calculate CT for eachsegment, where a disinfection segment isdefined as a treatment unit process with ameasurable disinfectant residual level and aliquid volume. Under this approach, systemsmust add the Cryptosporidium CT values ineach segment to determine the total CT forthe treatment plant.

(B) CT Values for Chlorine Dioxide andOzone.

1. Systems receive the Cryptosporidiumtreatment credit listed in this table by meetingthe corresponding chlorine dioxide CT valuefor the applicable water temperature, asdescribed in subsection (18)(A). Systemsmay use this equation to determine log creditbetween the indicated values:

Log credit = (0.001506 ×(1.09116)Temp) × CT



2. Systems receive the Cryptosporidiumtreatment credit listed in this table by meetingthe corresponding ozone CT values for theapplicable water temperature, as described insubsection (18)(A) of this rule.


Secretary of State


Log credit

Water temperature, C < 0.5

1 2 3 5 7 10 15 20 25 30

0.25 159 153 140 128 107 90 69 45 29 19 12 0.5 319 305 279 256 214 180 138 89 58 38 24 1.0 637 610 558 511 429 360 277 179 116 75 49 1.5 956 915 838 767 643 539 415 268 174 113 73

2.0 1275 1220 1117 1023 858 719 553 357 232 150 98 2.5 1594 1525 1396 1278 1072 899 691 447 289 188 122 3.0 1912 1830 1675 1534 1286 1079 830 536 347 226 147

CT Values (MG-MIN/L) for Cryptosporidium Inactivation By Chlorine Dioxide

CT Values (MG-MIN/L) for Cryptosporidium Inactivation by Ozone

Systems may use this equation to determine log credit between the indicated values: Log credit = (0.0397 × (1.09757) temp) × CT

Log credit Water Temperature, C

< 0.5

1 2 3 5 7 10 15 20 25 30

0.25 6.0 5.8 5.2 4.8 4.0 3.3 2.5 1.6 1.0 0.6 0.39

0.5 12 12 10 9.5 7.9 6.5 4.9 3.1 2.0 1.2 0.78

1.0 24 23 21 19 16 13 9.9 6.2 3.9 2.5 1.6

1.5 36 35 31 29 24 20 15 9.3 5.9 3.7 2.4

2.0 48 46 42 38 32 26 20 12 7.8 4.9 3.1

2.5 60 58 52 48 40 33 25 16 9.8 6.2 3.9

3.0 72 69 63 57 47 39 30 19 12 7.4 4.7

(C) Site-Specific Study. The departmentmay approve alternative chlorine dioxide orozone CT values to those listed in subsection(18)(B) on a site-specific basis. The depart-ment must base this approval on a site-specif-ic study a system conducts that follows adepartment-approved protocol.

(D) Ultraviolet Light. Systems receiveCryptosporidium, Giardia lamblia, andvirus-treatment credits for ultraviolet (UV)light reactors by achieving the correspondingUV dose values shown in paragraph(18)(D)1. Systems must validate and monitorUV reactors as described in paragraphs(18)(D)2. and 3. to demonstrate that they areachieving a particular UV dose value fortreatment credit.

1. UV dose table. The treatment creditslisted in this table are for UV light at a wave-length of two hundred fifty-four nanometers(254 nm) as produced by a low pressure mer-cury vapor lamp. To receive treatment creditfor other lamp types, systems must demon-strate an equivalent germicidal dose throughreactor validation testing, as described inparagraph (18)(D)2. of this rule. The UVdose values in this table are applicable only topost-filter applications of UV in filtered sys-tems.



UV Dose Table for Cryptosporidium, Giardia lamblia, and Virus Inactivation Credit

Log credit Cryptosporidium UV dose (mJ/cm2)

Giardia lamblia UV dose (mJ/cm2)

Virus UV dose (mJ/cm2)

0.5 1.6 1.5 39

1.0 2.5 2.1 58

1.5 3.9 3.0 79

2.0 5.8 5.2 100

2.5 8.5 7.7 121

3.0 12 11 143

3.5 15 15 163

4.0 22 22 186

2. Reactor validation testing. Systemsmust use UV reactors that have undergonevalidation testing to determine the operatingconditions under which the reactor deliversthe UV dose required in paragraph (18)(D)1.(i.e., validated operating conditions). Theseoperating conditions must include flow rate,UV intensity as measured by a UV sensor,and UV lamp status.

A. When determining validated oper-ating conditions, systems must account forthe following factors: UV absorbance of thewater; lamp fouling and aging; measurementuncertainty of online sensors; UV dose dis-tributions arising from the velocity profilesthrough the reactor; failure of UV lamps orother critical system components; and inletand outlet piping or channel configurations ofthe UV reactor.

B. Validation testing must include thefollowing: Full-scale testing of a reactor thatconforms uniformly to the UV reactors usedby the system and inactivation of a testmicroorganism whose dose response charac-teristics have been quantified with a low pres-sure mercury vapor lamp.

C. The department may approve analternative approach to validation testing.

3. Reactor monitoring requirements. A. Systems must monitor their UV

reactors to determine if the reactors are oper-ating within validated conditions, as deter-mined under paragraph (18)(D)2. This mon-itoring must include UV intensity as mea-sured by a UV sensor, flow rate, lamp status,and other parameters the department desig-nates based on UV reactor operation.Systems must verify the calibration of UVsensors and must recalibrate sensors in accor-dance with a protocol the departmentapproves.

B. To receive treatment credit for UVlight, systems must treat at least ninety-fivepercent (95%) of the water delivered to thepublic during each month by UV reactorsoperating within validated conditions for therequired UV dose, as described in paragraphs(18)(D)1. and 2. Systems must demonstratecompliance with this condition by the moni-toring required under subparagraph(18)(D)3.A. of this rule.

(19) Reporting Requirements.(A) Systems must report sampling sched-

ules under section (3) of this rule and sourcewater monitoring results under section (6) ofthis rule unless they notify the departmentthat they will not conduct source water mon-itoring due to meeting the criteria of subsec-tion (2)(D) of this rule.

(B) Filtered systems must report theirCryptosporidium bin classification as

described in section (10) of this rule. (C) Systems must report disinfection pro-

files and benchmarks to the department asdescribed in sections (8) through (9) of thisrule prior to making a significant change indisinfection practice.

(D) Systems must report to the departmentin accordance with the following table for anymicrobial toolbox options used to complywith treatment requirements under section(11) of this rule. Alternatively, the departmentmay approve a system to certify operationwithin required parameters for treatmentcredit rather than reporting monthly opera-tional data for toolbox options.


Secretary of State




Microbial Toolbox Reporting Requirements

Toolbox option

Systems must submit the following information

On the following schedule

Watershed control program (WCP)

(I) Notice of intention to develop a new or continue an existing watershed control program

No later than two years before the applicable treatment compliance date in section (12) of this rule

(II) Watershed control plan No later than one year before the applicable treatment compliance date in section (12) of this rule

(III) Annual watershed control program status report

Every 12 months, beginning one year after the applicable treatment compliance date in section (12) of this rule

(IV) Watershed sanitary survey report

For community water systems, every three years beginning three years after the applicable treatment compliance date in section (12) of this rule. For noncommunity water systems, every five years beginning five years after the applicable treatment compliance date in section (12) of this rule

Alternative source/intake management

Verification that system has relocated the intake or adopted the intake withdrawal procedure reflected in monitoring results

No later than the applicable treatment compliance date in section (12) of this rule

Presedimentation Monthly verification of the following: (I) Continuous basin operation; (II) Treatment of 100% of the flow; (III) Continuous addition of a coagulate; and (IV) At least 0.5-log mean reduction of influent turbidity or compliance with alternative department-approved performance criteria

Monthly reporting within 10 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

Two-stage lime softening Monthly verification of the following: (I) Chemical addition and hardness precipitation occurred in two separate and sequential softening stages prior to filtration; and (II) Both stages treated 100% of the plant flow

Monthly reporting within 10 days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in section (12) of this rule

Bank filtration (I) Initial demonstration of the following: (A) Unconsolidated, predominantly sandy aquifer; and (B) Setback distance of at least 25 ft. (0.5-log credit) or 50 ft. (1.0-log credit)


(II) If monthly average of daily max turbidity is greater than 1 NTU, then the system must report result and submit an assessment of the cause

Report within 30 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule


Secretary of State


Combined filter performance

Monthly verification of combined filter effluent (CFE) turbidity levels less than or equal to 0.15 NTU in at least 95% of the 4 hour CFE measurements taken each month

Monthly reporting within 10 days following the month in which the monitoring was conducted beginning on the applicable treatment compliance date in section (12) of this rule

Individual filter performance

Monthly verification of the following: (I) Individual filter effluent (IFE) turbidity levels less than or equal to 0.15 NTU in at least 95% of samples each month in each filter; and (II) No individual filter greater than 0.3 NTU in two consecutive readings 15 minutes apart

Monthly reporting within 10 days following the month in which the monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

Demonstration of performance

(I) Results from testing following a department approved protocol


(II) As required by the department, monthly verification of operation within conditions of department approval for demonstration of performance credit

Within 10 days following the month in which monitoring was conducted, beginning on the applicable treatment compliance date in section (12) of this rule

Bag filters and cartridge filters

(I) Demonstration that the following criteria are met: (A) Process meets the definition of bag or cartridge filtration; and (B) Removal efficiency established through challenge testing that meets criteria in this rule


(II) Monthly verification that 100% of plant flow was filtered


Membrane filtration (I) Results of verification testing demonstrating the following: (A) Removal efficiency established through challenge testing that meets criteria in this rule; and (B) Integrity test method and parameters, including resolution, sensitivity, test frequency, control limits, and associated baseline


(II) Monthly report summarizing the following: (A) All direct integrity tests above the control limit; and (B) If applicable, any turbidity or alternative department approved indirect integrity monitoring results triggering direct integrity testing and the corrective action that was taken


AUTHORITY: section 640.100, RSMo 2016.*Original rule filed Feb. 27, 2009, effectiveOct. 30, 2009. Amended: Filed June 13,2018, effective Feb. 28, 2019.


10 CSR 60-4.055 Disinfection Require-ments

PURPOSE: This rule establishes minimumdisinfectant levels and treatment requirementsto assure the inactivation and removal ofpathogenic organisms.

PUBLISHER’S NOTE: The secretary of statehas determined that the publication of theentire text of the material which is incorpo-rated by reference as a portion of this rulewould be unduly cumbersome or expensive.

This material as incorporated by reference inthis rule shall be maintained by the agency atits headquarters and shall be made availableto the public for inspection and copying at nomore than the actual cost of reproduction.This note applies only to the reference mate-rial. The entire text of the rule is printedhere.

(1) The requirements of this rule apply to pri-mary community and noncommunity publicwater systems that the department hasrequired to disinfect and to secondary sys-tems with a source of water from a primarywater system that the department has requiredto disinfect, even if the water is obtainedthrough another secondary system.

(A) Water systems using water obtained inwhole or in part from a source determined bythe department to be surface or ground waterunder the direct influence of surface watermust install or construct facilities to provide

conventional filtration treatment as a requiredtreatment technique within eighteen (18)months of the determination.

(B) Any water system that the departmentdetermines to be a groundwater system underthe direct influence of surface water mayappeal the decision by notifying the depart-ment in writing. The appeal must be accom-panied by a report prepared by an engineerthat confirms that the water system’s ground-water source is not directly influenced by sur-face water. The report must be supported byanalytical data prepared by a laboratory thatis acceptable to the department. Source sam-pling must be accomplished during the peri-od the source is most susceptible to surfacewater influence. The department’s approvalof the report will result in the water system’ssource being redefined as groundwater notunder the direct influence of surface water.

(C) If at any time in the department’s opin-ion, the quality of a water source appears to



Second stage filtration Monthly verification that 100% of flow was filtered through both stages and that first stage was preceded by coagulation step


Slow sand filtration (as secondary filter)

Monthly verification that both a slow sand filter and a preceding separate stage of filtration treated 100% of flow from surface water and ground water under the direct influence of surface water sources


Chlorine dioxide Summary of CT values for each day as described in section (18) of this rule


Ozone Summary of CT values for each day as described in section (18) of this rule


UV Validation test results demonstrating operating conditions that achieve required UV dose


Monthly report summarizing the percentage of water entering the distribution system that was not treated by UV reactors operating within validated conditions for the required dose specified in subsection (18)(D) of this rule


have changed to be under the direct influenceof surface water, the water system must sub-mit, at the department’s written request, anengineer-prepared report that describes thecurrent condition of the water source. If areport is not submitted, the source will bereclassified as groundwater supply under thedirect influence of surface water.

(D) The department reserves the authorityto make the final determination of whether ornot a source is defined as groundwater underthe direct influence of surface water.

(E) Primary systems which use waterobtained from groundwater not under thedirect influence of surface water and whichthe department requires to disinfect and sec-ondary public water systems do not have tomeet the requirements of section (2) of thisrule but may be required to provide disinfec-tion detention as deemed necessary by thedepartment. These systems also do not haveto submit reports to the department asrequired by 10 CSR 60-7.010(4) but mustmaintain the information on file at the systemtreatment plant or office.

(2) Contact Time and Removal Credit.(A) Any water system providing required

treatment, and existing water systems practic-ing conventional filtration treatment onFebruary 6, 1992, will be credited with99.68 percent (2.5 log) Giardia lamblia cystremoval and 99.0 percent (2.0 log) virusremoval, excluding the disinfection process,provided that they meet the turbidity maxi-mum contaminant levels in 10 CSR 60-4.050.A system may request additional credit fortreatment process removal or inactivation ofGiardia lamblia cysts and viruses by submit-ting a report prepared by an engineer to thedepartment including studies of Giardia cystand virus removal or inactivation. Thedepartment reserves the authority to make thefinal determination of removal credit.

(B) The residual disinfectant concentration(C) disinfectant contact time (T) values in theMissouri Guidance Manual for Surface WaterSystem Treatment Requirements, 1992, mustbe used for determining the percentage ofGiardia lamblia cyst and virus removal orinactivation by disinfection.

(C) The percentage of removal and inacti-vation of Giardia lamblia cysts and viruseswill be determined as the sum of the percentremovals and inactivations of the individualtreatment and disinfection processes. Thepercent removal and inactivation of Giardialamblia cysts must be at least 99.9 percent(3.0 log) and of viruses must be 99.99 per-cent (4.0 log).

(D) Disinfectant contact time must be deter-mined for each system by evaluations per-

formed as specified in the Missouri GuidanceManual for Surface Water System TreatmentRequirements, 1992, which is incorporatedby reference. Results of the evaluations,including the determined disinfectant contacttimes, must be submitted to the departmentfor review. The evaluation must be submittedwithin one (1) year of the date that the systemis covered by the requirements of this rule,except that new water treatment facilities willnot be issued a Final Approval of Constructionunder 10 CSR 60-3.010 until disinfection con-tact times are determined and submitted to thedepartment.

(3) For any water system adding a disinfec-tant, only free available chlorine or chlo-ramines will be accepted as the disinfectantentering the distribution system. The residualdisinfectant concentration in the water enter-ing the distribution system cannot be less than0.5 milligrams per liter (mg/L) free availablechlorine or 1.0 mg/L chloramines for morethan four (4) hours.

(A) Systems using chloramines as the dis-infectant residual entering the distributionsystem must add and mix the chlorine prior tothe addition of ammonia.

(B) At the department’s discretion, anysystem may be required to provide breakpointchlorination or to provide operational testdata and other information that the depart-ment may require to demonstrate that the sys-tem daily meets all of the requirements ofsection (2) of this rule and all of the otherrequirements of this section.

(C) At least one (1) application point forchlorine or chloramines must be prior to fil-tration with a residual maintained through thefilters.

(D) If at any time the disinfectant residualentering the distribution system falls belowthe levels established in this section, the sys-tem must notify the department as soon aspossible but no later than by the end of thenext business day. The system must notify thedepartment by the end of the next businessday whether or not the disinfectant residualwas restored to the levels established in thissection within four (4) hours. The departmentmay require public notice for continuing orpersistent violations of this requirement.

(E) A residual disinfectant concentration inthe water entering the distribution system ofless than 0.2 mg/L for at least four (4) hoursis a treatment technique violation whichrequires public notice pursuant to 10 CSR 60-8.010.

(F) The frequency of sampling shall be asset forth in 10 CSR 60-4.080(3).

(4) The residual disinfectant concentration in

the distribution system measured as totalchlorine or combined chlorine cannot be lessthan 0.2 mg/L in more than five percent (5%)of the samples each month for any two (2)consecutive months that the system supplieswater to the public.

(A) Heterotrophic plate count may be usedin lieu of or as a supplement to residual dis-infectant concentration analysis.

(B) Water in the distribution system with aheterotrophic bacteria concentration less thanor equal to five hundred (500) colonies permilliliter is deemed to have 0.2 mg/L residu-al disinfectant concentration for the purposeof determining compliance with this rule.

(C) Water in the distribution system with aheterotrophic bacteria concentration ofgreater than five hundred (>500) coloniesper milliliter is deemed to have less than 0.2mg/L residual disinfectant concentration forthe purpose of compliance with this rule.

(D) Failure to maintain the minimum resid-ual disinfectant concentration required in thisrule is a violation of a treatment techniquewhich requires public notification as speci-fied in 10 CSR 60-8.010.

(E) Public water systems that use chlorineor chloramines must measure the residualdisinfectant level in the distribution system atthe same point in the distribution system andat the same time as total coliforms are sam-pled, as specified in 10 CSR 60-4.022(4)-(8).Failure to comply with this subsection is amonitoring violation which requires publicnotification as specified in 10 CSR 60-8.010.

(5) Maximum Residual Disinfectant Levels. (A) Maximum residual disinfectant levels

(MRDL) applicable to all community andnontransient noncommunity water systemsusing chlorine, chloramines or chlorine diox-ide and to all transient noncommunity watersystems using chlorine dioxide are—

Disinfectant Residual MRDL (mg/L) Chlorine 4.0 (as Cl2)Chloramines 4.0 (as Cl2)Chlorine dioxide 0.8 (as ClO2)

(B) Control of Disinfectant Residuals. Forchlorine and chloramines, a public water sys-tem is in compliance with the MRDL whenthe running annual average of monthly aver-ages of samples taken in the distribution sys-tem, computed quarterly, is less than or equalto the MRDL. For chlorine dioxide, a publicwater system (PWS) is in compliance with theMRDL when daily samples are taken at theentrance to the distribution system and no two(2) consecutive daily samples exceed theMRDL. MRDLs are enforceable in the samemanner as maximum contaminant levels.Notwithstanding the MRDLs, systems may


Secretary of State


increase residual disinfectant levels in the dis-tribution system of chlorine or chloramines(but not chlorine dioxide) to a level and for atime necessary to protect public health, toaddress specific microbiological contamina-tion problems caused by circumstances suchas, but not limited to, distribution line breaks,storm run-off events, source water contami-nation events, or cross-connection events.

(6) Enhanced Disinfection Requirements. (A) In addition to the requirements in sec-

tions (1)–(4) of this rule, surface water andgroundwater under the direct influence ofsurface water systems must comply with therequirements in this section.

(B) General Requirements. 1. This section (6) establishes or extends

treatment technique requirements in lieu ofmaximum contaminant levels for the followingcontaminants: Giardia lamblia, viruses, het-erotrophic plate count bacteria, Legionella,Cryptosporidium, and turbidity. Each surfacewater and groundwater under the direct influ-ence of surface water system must providetreatment of its source water that complieswith these treatment technique requirementsand are in addition to those identified in sec-tions (1)–(4) of this rule. The treatment tech-nique requirements consist of installing andproperly operating water treatment processeswhich reliably achieve:

A. At least ninety-nine percent (99%)(2-log) removal of Cryptosporidium betweena point where the raw water is not subject torecontamination by surface water runoff anda point downstream before or at the first cus-tomer; and

B. Compliance with the profiling andbenchmark requirements under the provisionsof subsection (6)(C) of this rule.

2. A public water system subject to therequirements of this section (6) is in compli-ance with the requirements of paragraph(6)(B)1. of this rule if it meets the applicablefiltration requirements in 10 CSR 60-4.050and the disinfection requirements in sections(2)–(4) and subsection (6)(C) of this rule.

(C) Disinfection Profiling andBenchmarking.

1. Disinfection profile. A disinfectionprofile is a summary of Giardia lamblia inac-tivation through the treatment plant measuredthrough the course of a year. A public watersystem subject to the requirements of this sec-tion (6) must determine its total tri-halomethanes (TTHM) annual average and itsHAA5 annual average. The annual average isthe arithmetic average of the quarterly aver-ages of four (4) consecutive quarters of moni-toring. If the annual average exceeds the levelsin subparagraph (6)(C)1.D. then the require-

ments in paragraph (6)(C)2. apply.A. The TTHM annual average must

be the annual average during the same periodas is used for the HAA5 annual average.

B. The HAA5 annual average must bethe annual average during the same period asis used for the TTHM annual average.

(I) Those systems that have collect-ed four (4) quarters of HAA5 occurrence datathat meets the routine monitoring samplenumber and location requirements for TTHMin 10 CSR 60-4.094 may use those data todetermine whether the requirements of thissection apply.

(II) Those systems that did not col-lect four (4) quarters of HAA5 occurrencedata that meets the provisions of part(6)(C)1.B.(I) of this rule by March 31, 2000must either:

(a) Conduct monitoring forHAA5 that meets the routine monitoringsample number and location requirements forTTHM in 10 CSR 60-4.094 to determine theHAA5 annual average and whether therequirements of paragraph (6)(C)2. of thisrule apply; or

(b) Comply with all other provi-sions of this section as if the HAA5 monitor-ing had been conducted and the resultsrequired compliance with paragraph (6)(C)2.of this rule.

C. The system must submit data to thedepartment on the schedule required by thedepartment.

D. Any system having either a TTHMannual average greater than or equal to 0.064mg/L or an HAA5 annual average greaterthan or equal to 0.048 mg/L during the peri-od identified in subparagraphs (6)(C)1.A.and B. of this rule must comply with para-graph (6)(C)2. of this rule.

2. Disinfection profiling requirementsand compliance dates vary depending on sys-tem size. Surface water and groundwaterunder the direct influence of surface watersystems serving a population of more than tenthousand (10,000) must monitor profilingdata according to subparagraph (6)(C)2.B.through (6)(C)2.C. Surface water andgroundwater under the direct influence ofsurface water systems serving a population ofless than ten thousand (10,000) must monitorprofiling data according to subparagraph(6)(C)2.D.

A. Any system that meets the criteriain subparagraph (6)(C)1.D. of this rule mustdevelop a disinfection profile of its disinfec-tion practice for a period of up to three (3)years.

B. The system must monitor daily fora period of twelve (12) consecutive calendarmonths to determine the total logs of inacti-

vation for each day of operation, based on theCT99.9 values in Tables 1 through 8 of theMissouri Guidance Manual for Surface WaterSystem Treatment Requirements, 1992, asappropriate, through the entire treatmentplant. This system must begin this monitoringwhen requested by the department. As a min-imum, the system with a single point of dis-infectant application prior to entrance to thedistribution system must conduct the moni-toring set forth in this subparagraph(6)(C)2.B. A system with more than one (1)point of disinfectant application must conductthis monitoring for each disinfection seg-ment. The system must monitor the parame-ters necessary to determine the total inactiva-tion ratio, using analytical methods in 10CSR 60-5.010, as follows:

(I) The temperature of the disin-fected water must be measured once per dayat each residual disinfectant concentrationsampling point during peak hourly flow;

(II) If the system uses chlorine, thepH of the disinfected water must be measuredonce per day at each chlorine residual disin-fectant concentration sampling point duringpeak hourly flow;

(III) The disinfectant contacttime(s) must be determined for each day dur-ing peak hourly flow; and

(IV) The residual disinfectant con-centration(s) of the water before or at the firstcustomer and prior to each additional point ofdisinfection must be measured each day dur-ing peak hourly flow.

C. In lieu of the monitoring conduct-ed under the provisions of subparagraph(6)(C)2.B. of this rule to develop the disin-fection profile the system may elect to meetthe requirements of part (6)(C)2.C.(I) of thisrule. In addition to the monitoring conductedunder the provisions of subparagraph(6)(C)2.B. of this rule to develop the disin-fection profile, the system may elect to meetthe requirements of part (6)(C)2.C.(II) of thisrule.

(I) A PWS that has three (3) years ofexisting operational data may submit thosedata, a profile generated using those data, anda request that the department approve use ofthose data in lieu of monitoring under the pro-visions of paragraph (6)(C)2. of this rule. Thedepartment must determine whether theseoperational data are substantially equivalent todata collected under the provisions of subpara-graph (6)(C)2.B. of this rule. These data mustalso be representative of Giardia lamblia inac-tivation through the entire treatment plant andnot just of certain treatment segments. Untilthe department approves this request, the sys-tem is required to conduct monitoring underthe provisions of subparagraph (6)(C)2.B. of



this rule. (II) In addition to the disinfection

profile generated under subparagraph(6)(C)2.B. of this rule, a PWS that has exist-ing operational data may use those data todevelop a disinfection profile for additionalyears. Such systems may use these additionalyearly disinfection profiles to develop abenchmark under the provisions of paragraph(6)(C)3. of this rule. The department willdetermine whether these operational data aresubstantially equivalent to data collectedunder the provisions of subparagraph(6)(C)2.B. of this rule. These data must alsobe representative of inactivation through theentire treatment plant and not just of certaintreatment segments.

D. The system must monitor once perweek on the same calendar day, for a periodof twelve (12) consecutive calendar months,to determine the total logs of inactivation foreach week of operation, based on the CT99.9values in Tables 1 through 8 of the MissouriGuidance Manual for Surface Water SystemTreatment Requirements, 1992, as appropri-ate, through the entire treatment plant. As aminimum, the system with a single point ofdisinfectant application prior to entrance tothe distribution system must conduct themonitoring set forth in this subparagraph. Asystem with more than one (1) point of disin-fectant application must conduct this moni-toring for each disinfection segment. Thesystem must monitor the parameters neces-sary to determine the total inactivation ratio,using analytical methods in 10 CSR 60-5.010,as follows:

(I) The temperature of the disin-fected water must be measured at each resid-ual disinfectant concentration sampling pointduring peak hourly flow;

(II) If the system uses chlorine, thepH of the disinfected water must be measuredat each chlorine residual disinfectant concen-tration sampling point during peak hourlyflow;

(III) The disinfectant contact time(s)must be determined during peak hourly flow;and

(IV) The residual disinfectant con-centration(s) of the water before or at the firstcustomer and prior to each additional point ofdisinfection must be measured during peakhourly flow.

E. The system must calculate the totalinactivation ratio as follows:

(I) The system may determine thetotal inactivation ratio for the disinfectionsegment based on either of the followingmethods:

(a) Determine one (1) inactiva-tion ratio (CTcalc/CT99.9) before or at the

first customer during peak hourly flow; or(b) Determine successive

(CTcalc/CT99.9) values, representing sequen-tial inactivation ratios, between the point ofdisinfectant application and a point before orat the first customer during peak hourly flow.Under this alternative, the system must cal-culate the total inactivation ratio by determin-ing (CTcalc/CT99.9) for each sequence andthen adding the (CTcalc/CT99.9) valuestogether to determine ((CTcalc/CT99.9));and

(II) The system must determine thetotal logs of inactivation by multiplying thevalue calculated in part (6)(C)2.D.(I) of thisrule by three (3.0).

F. A system that uses either chlo-ramines or ozone for primary disinfectionmust also calculate the logs of inactivation forviruses using a method identified in the UnitedStates Environmental Protection Agency’sOffice of Water document, AlternativeDisinfectants and Oxidants Guidance Manual,Volume 99 Issue 14 of EPA 815-R, publishedApril 1999. This document is incorporated byreference without any later amendments ormodifications. To obtain a copy, contact theU.S. Government Printing Office at 732North Capitol Street NW, Washington, D.C.20401, toll free (866)512-1800 or by visitinghttps://bookstore.gpo.gov.

G. The system must retain disinfec-tion profile data in graphic form, as a spread-sheet, or in some other format acceptable tothe department for review as part of sanitarysurveys conducted by the department.

3. Disinfection benchmarking. A. Any system required to develop a

disinfection profile under the provisions ofparagraphs (6)(C)1. and 2. of this rule andthat decides to make a significant change toits disinfection practice must consult with thedepartment in writing prior to making suchchange. Significant changes to disinfectionpractice are:

(I) Changes to the point of disin-fection;

(II) Changes to the disinfectant(s)used in the treatment plant;

(III) Changes to the disinfectionprocess; and

(IV) Any other modification identi-fied by the department.

B. Any system that is modifying itsdisinfection practice must calculate its disin-fection benchmark using one (1) of the fol-lowing procedures:

(I) For each year of profiling datacollected and calculated under paragraph(6)(C)2. of this rule, the system must deter-mine the lowest average monthly Giardialamblia inactivation in each year of profiling

data. The system must determine the averageGiardia lamblia inactivation for each calen-dar month for each year of profiling data bydividing the sum of Giardia lamblia inactiva-tion by the number of values calculated forthat month; or

(II) The disinfection benchmark isthe lowest monthly average value (for systemswith one (1) year of profiling data) or averageof lowest monthly average values (for systemswith more than one (1) year of profiling data)of the monthly logs of Giardia lamblia inac-tivation in each year of profiling data.

C. A system that uses either chlo-ramines or ozone for primary disinfectionmust also calculate the disinfection bench-mark for viruses using a method approved bythe department.

D. The system must submit the fol-lowing information to the department as partof its consultation process:

(I) A description of the proposedchange;

(II) The disinfection profile forGiardia lamblia (and, if necessary, viruses)under paragraph (6)(C)2. of this rule andbenchmark as required by subparagraph(6)(C)3.B. of this rule; and

(III) An analysis of how the pro-posed change will affect the current levels ofdisinfection.

(D) Filtration Sampling Requirements. Apublic water system subject to the require-ments of this section (6) that provides con-ventional filtration treatment must conductcontinuous monitoring of turbidity for eachindividual filter as indicated in 10 CSR 60-4.050(2)(D)1.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed July 12, 1991, effectiveFeb. 6, 1992. Amended: Filed Feb. 1, 1996,effective Oct. 30, 1996. Amended: Filed Dec.15, 1999, effective Sept. 1, 2000. Amended:Filed March 17, 2003, effective Nov. 30,2003. Amended: Filed Aug. 12, 2015, effec-tive March 30, 2016. Amended: Filed June13, 2018, effective Feb. 28, 2019.


10 CSR 60-4.060 Maximum RadionuclideContaminant Levels and MonitoringRequirements

PURPOSE: This rule establishes maximumcontaminant levels and monitoring require-ments for radionuclides.

PUBLISHER’S NOTE: The secretary of state


Secretary of State


has determined that the publication of theentire text of the material which is incorporat-ed by reference as a portion of this rule wouldbe unduly cumbersome or expensive. Thismaterial as incorporated by reference in thisrule shall be maintained by the agency at itsheadquarters and shall be made available tothe public for inspection and copying at nomore than the actual cost of reproduction.This note applies only to the reference materi-al. The entire text of the rule is printed here.

(1) Maximum Contaminant Levels (MCL).(A) MCL for Combined Radium-226 and

Radium-228. The maximum contaminantlevel for combined radium-226 and radium-228 is five picocuries per liter (5 pCi/l). Thecombined radium-226 and radium-228 valueis determined by the addition of the results ofthe analysis for radium-226 and the analysisfor radium-228.

(B) MCL for Gross Alpha Particle Activity(Excluding Radon and Uranium). The maxi-mum contaminant level for gross alpha parti-cle activity (including radium-226 but exclud-ing radon and uranium) is fifteen picocuriesper liter (15 pCi/l).

(C) MCL for Beta Particle and PhotonRadioactivity.

1. The average annual concentration ofbeta particle and photon radioactivity fromman-made radionuclides in drinking watermust not produce an annual dose equivalentto the total body or any internal organ greaterthan four (4) millirem/year (mrem/year).

2. Except for the radionuclides listed inTable A, the concentration of man-maderadionuclides causing four (4) mrem totalbody or organ dose equivalents must be cal-culated on the basis of two (2) liter per daydrinking water intake using the one hundredsixty-eight (168) hour data list in “MaximumPermissible Body Burdens and MaximumPermissible Concentrations of Radionuclidesin Air and in Water for OccupationalExposure,” NBS (National Bureau ofStandards) Handbook 69 as amended August1963, U.S. Department of Commerce, whichis incorporated by reference without any lateramendments or modifications. If two (2) ormore radionuclides are present, the sum oftheir annual dose equivalent to the total bodyor to any organ shall not exceed four (4)mrem/year.

Table A.—Average Annual ConcentrationsAssumed to Produce a Total Body or

Organ Dose of Mrem/Year

Radionuclide Critical Organ pCi per LiterTritium Total body 20,000Strontium-90 Bone Marrow 8

(D) MCL for Uranium. The maximum

contaminant level for uranium is thirty micro-grams per liter (30 μg/l).

(E) Compliance Dates. Community watersystems (CWSs) must comply with the MCLslisted in subsections (1)(A)–(D) of this rule.Compliance shall be determined in accor-dance with the requirements of 10 CSR 60-5.010 and section (2) of this rule.

(2) Monitoring Frequency and ComplianceRequirements for Radionuclides inCommunity Water Systems.

(A) Monitoring and ComplianceRequirements for Gross Alpha ParticleActivity, Radium-226, Radium-228, andUranium.

1. Community water systems must con-duct initial monitoring to determine compli-ance with subsections (1)(A), (B) and (D) ofthis rule. For the purposes of monitoring forgross alpha particle activity, radium-226, andradium-228, the detection limits are:

A. The detection limit for gross alphaparticle activity is three (3) pCi/L;

B. The detection limit for radium-226is one (1) pCi/L; and

C. The detection limit for radium-228is one (1) pCi/L.

2. Applicability and sampling locationfor existing community water systems orsources. All existing CWSs using groundwa-ter, surface water, or systems using bothground and surface water must sample atevery entry point to the distribution systemthat is representative of all sources being used(hereafter called a sampling point) under nor-mal operating conditions. The system musttake each sample at the sample samplingpoint unless conditions make another sam-pling point more representative of eachsource.

3. Applicability and sampling locationfor new community water systems or sources.All new CWSs or CWSs that use a newsource of water must begin to conduct initialmonitoring for the new source within the firstquarter after initiating use of the source.CWSs must conduct more frequent monitor-ing when ordered by the department in theevent of possible contamination or whenchanges in the distribution system or treat-ment processes occur which may increase theconcentration of radioactivity in finishedwater.

4. Initial monitoring for gross alpha par-ticle activity, radium-226, radium-228, anduranium.

A. For gross alpha particle activity,uranium, radium-226, and radium-228 moni-toring, the department will waive the finaltwo (2) quarters of initial monitoring for asampling point if the results of the samples

from the previous two (2) quarters are belowthe detection limit.

B. If the average of the initial moni-toring results for a sampling point is abovethe MCL, the system must collect and ana-lyze quarterly samples at that sampling pointuntil the system has results from four (4) con-secutive quarters that are at or below theMCL, unless the system enters into anotherschedule as part of a formal complianceagreement with the department.

5. Reduced monitoring. Communitywater systems may reduce the future frequen-cy of monitoring from once every three (3)years to once every six (6) or nine (9) yearsat each sampling point, based on the follow-ing criteria.

A. If the average of the initial moni-toring results for each contaminant (that is,gross alpha particle activity, uranium, radi-um-226, or radium-228) is below the detec-tion limit specified in paragraph (2)(A)1. ofthis rule, the system must collect and analyzefor that contaminant using at least one (1)sample at that sampling point every nine (9)years.

B. For gross alpha particle activityand uranium, if the average of the initial mon-itoring results for each contaminant is at orabove the detection limit but at or below one-half (1/2) the MCL, the system must collectand analyze for that contaminant using atleast one (1) sample at that sampling pointevery six (6) years. For combined radium-226 and radium-228, the analytical resultsmust be combined. If the average of the com-bined initial monitoring results for radium-226 and radium-228 is at or above the detec-tion limit but at or below one-half (1/2) theMCL, the system must collect and analyzefor that contaminant using at least one (1)sample at that sampling point every six (6)years.

C. For gross alpha particle activityand uranium, if the average of the initial mon-itoring results for each contaminant is aboveone-half (1/2) the MCL but at or below theMCL, the system must collect and analyze atleast one (1) sample at that sampling pointevery three (3) years. For combined radium-226 and radium-228, the analytical resultsmust be combined. If the average of the com-bined initial monitoring results for radium-226 and radium-228 is above one-half (1/2)the MCL but at or below the MCL, the sys-tem must collect and analyze at least one (1)sample at that sampling point every three (3)years.

D. Systems must use the samples col-lected during the reduced monitoring periodto determine the monitoring frequency for



subsequent monitoring periods (for example,if a system’s sampling point is on a nine (9)-year monitoring period, and the sample resultis above one-half (1/2) the MCL, then thenext monitoring period for that samplingpoint is three (3) years).

E. If a system has a monitoring resultthat exceeds the MCL while on reduced mon-itoring, the system must collect and analyzequarterly samples at that sampling point untilthe system has results from four (4) consecu-tive quarters that are below the MCL, unlessthe system enters into another schedule aspart of a formal compliance agreement withthe department.

6. Compositing. To fulfill quarterlymonitoring requirements for gross alpha par-ticle activity, radium-226, radium-228, oruranium, a system may composite up to four(4) consecutive quarterly samples from a sin-gle entry point if analysis is done within ayear of the first sample. The department willtreat analytical results from the compositedas the average analytical result to determinecompliance with the MCLs and the futuremonitoring frequency. If the analytical resultfrom the composited sample is greater thanone-half (1/2) the MCL, the department maydirect the system to take additional quarterlysamples before allowing the system to sampleunder a reduced monitoring schedule.

7. Gross alpha particle activity measure-ment.

A. A gross alpha particle activitymeasurement may be substituted for therequired radium-226 measurement providedthat the measured gross alpha particle activi-ty does not exceed five (5) pCi/L. A grossalpha particle activity measurement may besubstituted for the required uranium measure-ment provided that the measured gross alphaparticle activity does not exceed fifteen (15)pCi/L.

B. The gross alpha measurement shallhave a confidence interval of ninety-five per-cent (95%) (1.65s, where s is the standarddeviation of the net counting rate of the sam-ple) for radium-226 and uranium. When asystem uses a gross alpha particle activitymeasurement in lieu of a radium-226 and/oruranium measurement, the gross alpha parti-cle activity analytical result will be used todetermine the future monitoring frequencyfor radium-226 and/or uranium. If the grossalpha particle activity result is less thandetection, one-half (1/2) the detection limitwill be used to determine compliance and thefuture monitoring frequency.

(B) Monitoring and ComplianceRequirements for Beta Particle and PhotonRadioactivity. To determine compliance withthe maximum contaminant levels in subsec-

tion (1)(C) of this rule for beta particle andphoton radioactivity, a system must monitorat a frequency as follows:

1. Community water systems (both sur-face and ground water) designated by thedepartment as vulnerable must sample forbeta particle and photon radioactivity.Systems must collect quarterly samples forbeta emitters and annual samples for tritiumand strontium-90 at each entry point to thedistribution system (hereafter called a sam-pling point), beginning within one (1) quarterafter being notified by the department.Systems already designated by the depart-ment must continue to sample until thedepartment reviews and either reaffirms orremoves the designation.

A. If the gross beta particle activityminus the naturally occurring potassium-40beta particle activity at a sampling point hasa running annual average (computed quarter-ly) less than or equal to fifty (50) pCi/L(screening level), the department may reducethe frequency of monitoring at that samplingpoint to once every three (3) years. Systemsmust collect all samples required in para-graph (2)(B)1. of this rule during the reducedmonitoring period.

B. For systems in the vicinity of anuclear facility, the department may allow theCWS to use environmental surveillance datacollected by the nuclear facility in lieu ofmonitoring at the system’s entry point(s),where the department determines such data isapplicable to the community water system. Inthe event that there is a release from a nucle-ar facility, systems, using surveillance datamust begin monitoring at the communitywater system’s entry point(s) in accordancewith paragraph (2)(B)1. of this rule.

2. Community water systems (both sur-face and ground water) designated by thedepartment as using waters contaminated byeffluents from nuclear facilities must samplefor beta particle and photon radioactivity.Systems must collect quarterly samples forbeta emitters and iodine-131 and annual sam-ples for tritium and strontium-90 at eachentry point to the distribution system (here-after called a sampling point), beginningwithin one (1) quarter after being notified bythe department. Systems already designatedby the department as systems using waterscontaminated by effluents from nuclear facil-ities shall continue to sample until the depart-ment reviews and either reaffirms or removesthe designation.

A. Quarterly monitoring for grossparticle activity shall be based on the analy-sis of monthly samples or the analysis of acomposite of three (3) monthly samples. Theformer is recommended.

B. For iodine-131, a composite of five(5) consecutive daily samples shall be ana-lyzed once each quarter. As ordered by thedepartment, more frequent monitoring shallbe conducted when iodine-131 is identified inthe finished water.

C. Annual monitoring for strontium-90 and tritium shall be conducted by meansof analysis of four (4) quarterly samples, orwith department approval, a composite ofsamples collected in four (4) consecutivequarters.

D. If the gross beta particle activityminus the naturally occurring potassium-40beta particle activity at a sampling point hasa running annual average (computed quarter-ly) less than or equal to fifteen (15) pCi/l, thedepartment may reduce the frequency ofmonitoring at that sampling point to everythree (3) years. Systems must collect all sam-ples required in paragraph (2)(B)2. of thisrule during the reduced monitoring period.

E. For systems in the vicinity of anuclear facility, the department may allow theCWSs to utilize environmental surveillancedata collected by the nuclear facility in lieu ofmonitoring at the system’s entry point(s),where the department determines if such datais applicable to the water system. In the eventthat there is a release from a nuclear facility,systems using surveillance data must beginmonitoring at the community water system’sentry point(s) in accordance with paragraph(2)(B)2. of this rule.

3. Community water systems designatedby the department to monitor for beta particleand photon radioactivity shall not apply to thedepartment for a waiver from the monitoringfrequencies specified in paragraph (2)(B)1.or (2)(B)2. of this rule.

4. Community water systems may ana-lyze for naturally occurring potassium-40beta particle activity from the same or equiv-alent sample used for the gross beta particleactivity analysis. Systems are allowed to sub-tract the potassium-40 beta particle activityvalue from the total gross beta particle activ-ity value to determine if the screening level isexceeded. The potassium-40 beta particleactivity must be calculated by multiplyingelemental potassium concentrations (in mg/l)by a factor of 0.82.

5. If the gross beta particle activityminus the naturally occurring potassium-40beta particle activity exceeds the screeninglevel, an analysis of the sample must be per-formed to identify the major radioactive con-stituents present in the sample and the appro-priate doses must be calculated and summedto determine compliance with paragraph(1)(C)1., using the formula in paragraph(1)(C)2. Doses must also be calculated and


Secretary of State


combined for measured levels of tritium andstrontium to determine compliance.

6. Systems must monitor monthly at thesampling point(s) which exceed the maximumcontaminant level in subsection (1)(C) begin-ning the month after the exceedance occurs.Systems must continue monthly monitoringuntil the system has established, by a rollingaverage of three (3) monthly samples, that theMCL is being met. Systems who establishthat the MCL is being met must return toquarterly monitoring until they meet therequirements set forth in subparagraph(2)(B)1.B. or subparagraph (2)(B)2.A of thisrule.

(C) General Monitoring and ComplianceRequirements for Radionuclides.

1. The department may require morefrequent monitoring than specified in subsec-tions (2)(A) and (2)(B) of this rule, or mayrequire confirmation samples at its discre-tion. The results of the initial and confirma-tion samples will be averaged for use in com-pliance determinations.

2. Each public water system shall moni-tor at the time designated by the departmentduring each compliance period.

3. Compliance with subsections (1)(A)–(D) of this rule will be determined based onthe analytical result(s) obtained at each sam-pling point. If one (1) sampling point is inviolation of an MCL, the system is in viola-tion of the MCL.

A. For systems monitoring more thanonce per year, compliance with the MCL isdetermined by a running annual average ateach sampling point. If the average of anysampling point is greater than the MCL, thenthe system is out of compliance with theMCL.

B. For systems monitoring more thanonce per year, if any sample result will causethe running average to exceed the MCL at anysample point, the system is out of compliancewith the MCL immediately.

C. Systems must include all samplestaken and analyzed under the provisions ofthis section in determining compliance, evenif that number is greater than the minimumrequired.

D. If a system does not collect allrequired samples when compliance is basedon a running annual average of quarterly sam-ples, compliance will be based on the runningaverage of the samples collected.

E. If a sample result is less than thedetection limit, zero (0) will be used to cal-culate the annual average, unless a grossalpha particle activity is being used in lieu ofradium-226 and/or uranium. If the grossalpha particle activity result is less thandetection, one-half (1/2) the detection limit

will be used to calculate the annual average. 4. The department has the discretion to

delete results of obvious sampling or analyticerrors.

5. If the MCL for radioactivity set forthin subsection (1)(A)–(D) of this rule isexceeded, the operator of a community watersystem must give notice to the departmentpursuant to 10 CSR 60-7.010 and to the pub-lic as required by 10 CSR 60-8.010.

(3) Non-Community Water Systems. Non-community water systems must monitor forradionuclides as directed by the department.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed May 4, 1979, effectiveSept. 14, 1979. Amended: Filed April 14,1981, effective Oct. 11, 1981. Rescinded andreadopted: Filed Jan. 16, 2002, effective Nov.30, 2002. Amended: Filed June 13, 2018,effective Feb. 28, 2019.


10 CSR 60-4.070 Secondary ContaminantLevels and Monitoring Requirements

PURPOSE: This rule establishes maximumcontaminant levels and monitoring require-ments for secondary contaminants.

(1) The following are the recommended sec-ondary maximum contaminant levels forcommunity and nontransient noncommunitywater systems:

Contaminant LevelAluminum 0.05–0.2 mg/l Chloride 250 mg/l Color 15 color units Copper 1.0 mg/lCorrosivity Noncorrosive Fluoride 2.0 mg/l Foaming agents 0.5 mg/l Iron 0.3 mg/l Manganese 0.05 mg/l Odor 3 Threshold Odor

numberpH 6.5–8.5 Silver 0.1 mg/l Sulfate 250 mg/l Total dissolved solids (TDS) 500 mg/lZinc 5 mg/l

(2) Groundwater systems shall take one (1)sample at each sampling point during eachthree (3)-year compliance period beginningin the compliance period starting January 1,1993. Surface water systems (or combined

surface/ground) shall take one (1) sampleannually at each sampling point beginningJanuary 1, 1993. Color, foaming agents andodor should be analyzed at the water systemsite, as needed.

(3) For community water systems, if theresult of analyses indicates that the secondarycontaminant level for fluoride is exceeded,the supplier of water must report to thedepartment within seven (7) days and mustcollect three (3) additional samples from des-ignated sampling points to be submitted foranalysis within one (1) month at intervalsdetermined by the department. When theaverage of the results of four (4) analyses asrequired by this section exceeds the sec-ondary contaminant level, the supplier ofwater must notify the department as requiredby 10 CSR 60-7.010 and give notice asrequired by 10 CSR 60-8.010.

AUTHORITY: section 640.100, RSMo Supp.2002.* Original rule filed May 4, 1979,effective Sept. 14, 1979. Amended: FiledApril 14, 1981, effective Oct. 11, 1981.Amended: Filed Aug. 4, 1987, effective Jan.1, 1988. Rescinded and readopted: FiledMarch 31, 1992, effective Dec. 3, 1992.Amended: Filed March 17, 2003, effectiveNov. 30, 2003.


10 CSR 60-4.080 Operational Monitoring

PURPOSE: This rule establishes criteria foroperation and operational monitoring.

PUBLISHER’S NOTE: The secretary of statehas determined that the publication of theentire text of the material which is incorpo-rated by reference as a portion of this rulewould be unduly cumbersome or expen-sive. This material as incorporated by refer-ence in this rule shall be maintained by theagency at its headquarters and shall be madeavailable to the public for inspection andcopying at no more than the actual cost ofreproduction. This note applies only to thereference material. The entire text of the ruleis printed here.

(1) Public water systems utilizing any treat-ment process must perform sufficient analy-ses to maintain control of the treatment pro-cess, using methods as required by 10 CSR60-5.010 and as acceptable to the department.

(2) Automatic instrumentation may be used ifproperly installed, maintained and periodically



calibrated against known standards preparedin accordance with Standard Methods for theExamination of Water and Wastewater 1992,18th edition, or Methods for ChemicalAnalysis of Water and Wastes, published inMarch 1983 by the Environmental ProtectionAgency’s (MCAWW, Section 9.3,EPA/600/479/020, Cincinnati, OH). Thisdocument is incorporated by reference with-out any later amendments or modifications.To obtain a copy, contact the U.S.Government Printing Office at 732 NorthCapitol Street NW, Washington, D.C.,20401, toll free at (866)512-1800 or by visit-ing https://bookstore.gpo.gov.

(3) Sufficient analyses must be done to assurecontrol of water quality, the followingrequirements notwithstanding. Continuousmonitoring and recording may be used forany operational analysis instead of grab sam-pling provided that the requirements of sec-tion (2) are met. For those analyses wherecontinuous monitoring is required, if there isa failure in the continuous monitoring equip-ment, grab sampling every four (4) hours ofoperation may be conducted in lieu of contin-uous monitoring but for no more than five (5)working days following the failure of theequipment. Applicable analyses and testingfrequencies are as follows:


Secretary of State



Secretary of State


(4) If, after investigation, the departmentfinds that any public water system is incom-petently supervised, improperly operated,inadequate, of defective design or if the waterfails to meet standards established in theserules, the water supplier must implementchanges that may be required by the depart-ment.

(5) Every supplier of water to a public watersystem must disinfect all newly constructedor repaired water distribution mains, finishedwater storage facilities or wells by methodsacceptable to the department before beingplaced in or returned to service.

(6) All finished water reservoirs must be cov-ered by a permanent, protective material,adequately vented with properly screenedopenings.

(7) Chemicals, materials and protective coat-ings used in public water systems must beacceptable to the department.

(8) Public water systems must maintain aminimum positive pressure of twenty poundsper square inch (20 psi) throughout the dis-tribution system under all normal operatingconditions.

(9) A supplier of water that adds fluoride tothe water system must submit one (1) sampleper quarter for analyses to an approved labo-ratory.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed May 4, 1979, effectiveSept. 14, 1979. Amended: Filed April 14,1981, effective Oct. 11, 1981. Amended: FiledJuly 12, 1991, effective Feb. 6, 1992.Amended: Filed Feb. 1, 1996, effective Oct.30, 1996. Amended: Filed June 13, 2018,effective Feb. 28, 2019.


10 CSR 60-4.090 Maximum ContaminantLevels and Monitoring Requirements forDisinfection By-Products(Rescinded February 28, 2019)

AUTHORITY: section 640.100, RSMo Supp.2008. Original rule filed April 14, 1981,effective Oct. 11, 1981. Amended: Filed Feb.1, 1996, effective Oct. 30, 1996. Amended:Filed Dec. 15, 1999, effective Sept. 1, 2000.Amended: Filed March 17, 2003, effectiveNov. 30, 2003. Amended: Filed Feb. 27,2009, effective Oct. 30, 2009. Rescinded:Filed June 13, 2018, effective Feb. 28, 2019.

10 CSR 60-4.092 Initial DistributionSystem Evaluation(Rescinded September 30, 2018)

AUTHORITY: section 640.100, RSMo Supp.2008. Original rule filed Feb. 27, 2009, effec-tive Oct. 30, 2009. Rescinded: Filed Dec. 29,2017, effective Sept. 30, 2018.

10 CSR 60-4.094 Disinfectant Residuals,Disinfection Byproduct Precursors andthe Stage 2 Disinfectants/DisinfectionByproducts Rule

PURPOSE: This rule establishes monitoringand other requirements for achieving compli-ance with maximum contaminant levels basedon locational running annual averages forcertain disinfection byproducts and forachieving compliance with maximum residualdisinfectant levels for chlorine and chlo-ramine for certain consecutive systems. Thisrule incorporates the requirements of sub-parts L and V of 40 CFR part 141, Stage 2Disinfectants/Disinfection Byproducts, pub-lished in the January 4, 2006, FederalRegister.

(1) Stage 2 Disinfectants/DisinfectionByproducts (D/DBP) Rule GeneralRequirements.

(A) The requirements of this rule constitutenational primary drinking water regulations.This rule establishes monitoring and otherrequirements for achieving compliance withmaximum contaminant levels based on loca-tional running annual averages (LRAA) fortotal trihalomethanes (TTHM) and haloaceticacids five (HAA5), and for achieving compli-ance with maximum residual disinfectantresiduals for chlorine and chloramine for cer-tain consecutive systems.

(B) Applicability. This rule applies tocommunity water systems and nontransientnoncommunity water systems that use a pri-mary or residual disinfectant other than ultra-violet light or deliver water that has beentreated with a primary or residual disinfectantother than ultraviolet light.

(C) Community water systems and non-transient noncommunity water systems mustcomply with maximum residual disinfectantlevels (MRDLs), monitoring and compliancerequirements of this rule, and the MCLs of0.080 mg/L for total triahalomethanes(TTHM), 0.060 mg/L for haloacetic acids(five) (HAA5), 0.010 mg/L for bromate, and1.0 mg/L for chlorite.

(2) Monitoring Requirements.(A) Disinfectant Residuals, Chlorite, and

Bromate Monitoring Requirements. 1. Chlorine and chloramines.

A. Routine monitoring. Communityand nontransient noncommunity water sys-tems must measure the residual disinfectantlevel at the same points in the distributionsystem and at the same time as total coliformsare sampled, as specified in 10 CSR 60-4.022. Systems using surface water or groundwater under the direct influence of surfacewater may use the results of residual disin-fectant concentration sampling conductedunder 10 CSR 60-4.080(3) and 10 CSR 60-4.055(4), in lieu of taking separate samples.

B. Reduced monitoring. Monitoringmay not be reduced.

2. Chlorine dioxide. A. Routine monitoring. Community,

nontransient noncommunity, and transientnoncommunity water systems that use chlo-rine dioxide for disinfection or oxidationmust take daily samples at the entrance to thedistribution system. For any daily sample thatdetects chlorine dioxide, the system must takeadditional samples in the distribution systemthe following day in addition to the samplerequired at the entrance to the distributionsystem.

B. Additional monitoring. On eachday following a routine sample monitoringresult that detects chlorine dioxide, the sys-tem is required to take three (3) chlorinedioxide distribution system samples as closeto the first customer as possible, at intervalsof at least six (6) hours. If chloramines areused to maintain a disinfectant residual in thedistribution system, or if chlorine is used tomaintain a disinfectant residual in the distri-bution system and there are no disinfectionaddition points after the entrance to the dis-tribution system (that is, no booster chlorina-tion), the system must take three (3) samplesas close to the first customer as possible, atintervals of at least six (6) hours. If chlorineis used to maintain a disinfectant residual inthe distribution system and there are one (1)or more disinfection addition points after theentrance to the distribution system (that is,booster chlorination), the system must takeone (1) sample at each of the following loca-tions: as close to the first customer as possi-ble; in a location representative of averageresidence time; and as close to the end of thedistribution system as possible (reflectingmaximum residence time in the distributionsystem).

C. Reduced monitoring. Chlorinedioxide monitoring may not be reduced.

3. Chlorite. A. Routine monitoring. Community

and nontransient noncommunity water sys-tems using chlorine dioxide, for disinfection



or oxidation, must conduct monitoring forchlorite.

(I) Daily Monitoring. Systems musttake daily samples at the entrance to the dis-tribution system. For any daily sample thatexceeds the chlorite MCL, the system musttake additional samples in the distributionsystem the following day at the followinglocations: near the first customer; at a loca-tion representative of average residence time;and at a location reflecting maximum resi-dence time in the distribution system, in addi-tion to the sample required at the entrance tothe distribution system.

(II) Monthly monitoring. Systemsmust take a three (3)-sample set each monthin the distribution system. The system musttake one (1) sample at each of the followinglocations: near the first customer; at a loca-tion representative of average residence time;and at a location reflecting maximum resi-dence time in the distribution system. Anyadditional routine sampling must be conduct-ed in the same manner (as three (3)-samplesets, at the specified locations). The systemmay use the results of additional monitoringconducted under the following subparagraph(2)(A)3.B. to meet the requirement formonthly monitoring.

B. Additional monitoring. On eachday following a routine sample monitoringresult that exceeds the chlorite MCL at theentrance to the distribution system, the sys-tem is required to take three (3) chlorite dis-tribution system samples at the followinglocations: as close to the first customer aspossible, in a location representative of aver-age residence time, and as close to the end ofthe distribution system as possible (reflectingmaximum residence time in the distributionsystem).

C. Reduced monitoring.(I) Chlorite monitoring at the

entrance to the distribution system requiredby part (2)(A)3.A.(I) of this rule may not bereduced.

(II) Chlorite monitoring in the dis-tribution system required by part(2)(A)3.A.(II) of this rule may be reduced toone (1) three (3)-sample set per quarter afterone (1) year of monitoring where no individ-ual chlorite sample taken in the distributionsystem under part (2)(A)3.A.(II) of this rulehas exceeded the chlorite MCL and the sys-tem has not been required to conduct moni-toring under subparagraph (2)(A)3.B. of thisrule. The system may remain on the reducedmonitoring schedule until either any of thethree (3) individual chlorite samples takenquarterly in the distribution system underpart (2)(A)3.A.(II) of this rule exceeds thechlorite MCL or the system is required to

conduct monitoring under subparagraph(2)(A)3.B. of this rule, at which time the sys-tem must revert to routine monitoring.

4. Bromate.A. Routine monitoring. Community

and nontransient noncommunity systemsusing ozone for disinfection or oxidationmust take one (1) sample per month for eachtreatment plant in the system using ozone.Systems must take samples monthly at theentrance to the distribution system while theozonation system is operating under normalconditions.

B. Reduced monitoring. A systemrequired to analyze for bromate may reducemonitoring from monthly to quarterly, if thesystem’s running annual average bromateconcentration is less than or equal to 0.0025mg/L based on monthly bromate measure-ments for the most recent four (4) quarters,with samples analyzed using Method 317.0Revision 2.0, 326.0, or 321.8. If a system hasqualified for reduced bromate monitoring,that system may remain on reduced monitor-ing as long as the running annual average ofquarterly bromate samples is ≤0.0025 mg/Lbased on samples analyzed using Method317.0 Revision 2.0, 326.0, or 321.8. If therunning annual average bromate concentra-tion is >0.0025 mg/L, the system mustresume routine monitoring required by sub-paragraph (2)(A)4.A. of this rule.

(B) Disinfection Byproduct Precursors(DBPP) Monitoring Requirements.

1. Total Organic Carbon (TOC).A. Routine Monitoring. Systems

using surface water or ground water underthe direct influence of surface water andusing conventional filtration treatment mustmonitor each treatment plant for total organ-ic carbon (TOC) no later than the point ofcombined filter effluent turbidity monitoringand representative of the treated water. Thesesystems must also monitor for TOC in thesource water prior to any treatment at thesame time as monitoring for TOC in the treat-ed water. These samples (source water andtreated water) are referred to as paired sam-ples. At the same time as the source watersample is taken, all systems must monitor foralkalinity in the source water prior to anytreatment. Systems must take one (1) pairedsample and one (1) source water alkalinitysample per month per plant at a time repre-sentative of normal operating conditions andinfluent water quality.

B. Reduced monitoring. Systemsusing surface water or ground water underthe direct influence of surface water with anaverage treated water TOC of less than 2.0mg/L for two (2) consecutive years, or lessthan 1.0 mg/L for one (1) year, may reduce

monitoring for both TOC and alkalinity toone (1) paired sample and one (1) sourcewater alkalinity sample per plant per quarter.The system must revert to routine monitoringin the month following the quarter when theannual average treated water TOC greaterthan or equal to 2.0 mg/L.

2. Bromide. Systems required to analyzefor bromate may reduce bromate monitoringfrom monthly to once per quarter, if the sys-tem demonstrates that the average sourcewater bromide concentration is less than 0.05mg/L based upon representative monthlymeasurements for one (1) year. The systemmust continue bromide monitoring to remainon reduced bromate monitoring.

(C) Total Trihalomethane and HaloaceticAcid Monitoring Requirements.

1. General Requirements.A. Undisinfected systems that begins

using a disinfectant other than ultraviolet(UV) light must consult with the departmentto identify compliance monitoring locationsfor this rule. Systems must then develop amonitoring plan that includes those monitor-ing locations.

B. Stage 2 D/DBP ComplianceMonitoring Plan.

(I) Developing and implementing amonitoring plan. The system must developand implement a monitoring plan to be kepton file for department and public review.Unless otherwise directed by the department,the monitoring plan must contain the follow-ing elements and be complete no later thanthe date initial monitoring under this rule isconducted:

(a) Monitoring locations; (b) Monitoring dates; (c) Compliance calculation pro-

cedures; and (d) Monitoring plans for any

other systems in the combined distributionsystem if the department has reduced moni-toring requirements.

(II) The system must identify whichlocations to use for Stage 2 D/DBP rule com-pliance monitoring by alternating selection oflocations representing high TTHM levels andhigh HAA5 levels until the required numberof Stage 2 D/DBP rule compliance monitor-ing locations have been identified.

(III) The system must submit acopy of the monitoring plan to the departmentprior to the date the system conducts the ini-tial monitoring under this rule.

(IV) A system may revise the mon-itoring plan to reflect changes in treatment,distribution system operations and layout(including new service areas), or other fac-tors that may affect TTHM or HAA5 forma-tion, or for department-approved reasons,


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after consultation with the departmentregarding the need for changes and the appro-priateness of changes. If the system changesmonitoring locations, the system must replaceexisting compliance monitoring locationswith the lowest LRAA with new locationsthat reflect the current distribution systemlocations with expected high TTHM orHAA5 levels. The department may alsorequire modifications in the system’s moni-toring plan. The system must submit a copyof the modified monitoring plan to the depart-ment prior to the date the system is requiredto comply with the revised monitoring plan.

C. Monitoring must begin at the loca-tions and months the system has recommend-ed in the Stage 2 D/DBP ComplianceMonitoring Plan unless the departmentrequires other locations or additional loca-tions after its review.

D. Analytical methods. The systemmust use an approved method listed in 10CSR 60-5.010 for TTHM and HAA5 analy-ses. Analyses must be conducted by laborato-ries that have received certification byEnvironmental Protection Agency (EPA) orthe department as specified in 10 CSR 60-5.020.

E. Additional Requirements forConsecutive Systems. If the system is a con-secutive system that does not add a disinfec-tant but delivers water that has been treatedwith a primary or residual disinfectant otherthan ultraviolet light, the system must complywith analytical and monitoring requirementsfor chlorine and chloramines in 10 CSR 60-5.010 and 10 CSR 60-4.055(4)(E), the com-pliance requirements in 10 CSR 60-4.094(3)(B.)1. and report monitoring resultsunder 10 CSR 60-7.010(5)(B).



2. Reduced Monitoring. A. Monitoring requirements for

source water TOC. In order to qualify forreduced monitoring for TTHM and HAA5,surface water and ground water under thedirect influence of surface water (GWUD-ISW) systems not monitoring under the TOCreduced monitoring provisions, must takemonthly TOC samples every thirty (30) daysat a location prior to any treatment. Oncequalified for reduced monitoring for TTHMand HAA5, a system may reduce sourcewater TOC monitoring to quarterly TOCsamples taken every ninety (90) days at alocation prior to any treatment.

B. The system may reduce monitoringany time the LRAA is ≤0.040 mg/L forTTHM and ≤0.030 mg/L for HAA5 at allmonitoring locations. In addition, the sourcewater annual average TOC level, before anytreatment, must be ≤4.0 mg/L at each treat-ment plant treating surface water or groundwater under the direct influence of surfacewater.


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Source water type

Population size category

Monitoring Frequency1

Distribution system monitoring location per monitoring period

Surface water system or ground water under the direct influence of surface water: Ground water:

<500 500–3,300 3,301–9,999 10,000–49,999 50,000–249,999 250,000–999,999 1,000,000–4,999,999

5,000,000 <500 500-9,999 10,000-99,999 100,000-499,999

500,000

………… Per year Per year Per quarter Per quarter Per quarter Per quarter Per quarter Every third year Per year Per year Per quarter Per quarter

Monitoring may not be reduced. 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. 2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement; and one at the location and during the quarter with the highest HAA5 single measurement. 2 dual sample sets at the locations with the highest TTHM and highest HAA5 LRAAs. 4 dual sample sets—at the locations with the two highest TTHM and two highest HAA5 LRAAs. 6 dual sample sets—at the locations with the three highest TTHM and three highest HAA5 LRAAs. 8 dual sample sets—at the locations with the four highest TTHM and four highest HAA5 LRAAs. 10 dual sample sets—at the locations with the five highest TTHM and five highest HAA5 LRAAs. 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. 2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement; and one at the location and during the quarter with the highest HAA5 single measurement. 2 dual sample sets; at the locations with the highest TTHM and highest HAA5 LRAAs. 4 dual sample sets at the locations with the two highest TTHM and two highest HAA5 LRAAs.

Stage 2 D/DBP Reduced Monitoring

1 Systems on quarterly monitoring must take dual sample sets every 90 days.

C. The system may remain onreduced monitoring as long as the TTHMLRAA ≤0.040 mg/L and the HAA5 LRAA≤0.030 mg/L at each monitoring location(for systems with quarterly reduced monitor-ing) or each TTHM sample ≤0.060 mg/Land each HAA5 sample ≤0.045 mg/L (forsystems with annual or less frequent monitor-ing). In addition, the source water annualaverage TOC level, before any treatment,must be ≤4.0 mg/L at each treatment planttreating surface water or ground water underthe direct influence of surface water.

D. If the LRAA based on quarterlymonitoring at any monitoring locationexceeds either 0.040 mg/L for TTHM or0.030 mg/L for HAA5 or if the annual (orless frequent) sample at any location exceedseither 0.060 mg/L for TTHM or 0.045 mg/Lfor HAA5, or if the source water annual aver-age TOC level, before any treatment, >4.0mg/L at any treatment plant treating surfacewater or ground water under the direct influ-ence of surface water, the system mustresume routine monitoring under section 10CSR 60-4.094(2)(C)2. or begin increasedmonitoring if paragraph 10 CSR 60-4.094(2)(C)4. applies.

E. The department may return thesystem to routine monitoring at the depart-ment’s discretion.

3. Increased Monitoring. A. If the system is required to moni-

tor at a particular location annually or lessfrequently than annually under routine orreduced monitoring of this rule, the systemmust increase monitoring to dual sample setsonce per quarter (taken every ninety (90)days) at all locations if a TTHM sample is>0.080 mg/L or an HAA5 sample is>0.060 mg/L at any location.

B. The system is in violation of theMCL when the LRAA exceeds the Stage 2D/DBP rule MCLs in subparagraph 10 CSR60-4.094(3)(D)3.A., calculated based onfour (4) consecutive quarters of monitoring(or the LRAA calculated based on fewer thanfour (4) quarters of data if the MCL would beexceeded regardless of the monitoring resultsof subsequent quarters). The system is in vio-lation of the monitoring requirements foreach quarter that a monitoring result wouldbe used in calculating an LRAA if the systemfails to monitor.

C. The system may return to routinemonitoring once the system has conductedincreased monitoring for at least four (4) con-secutive quarters and the LRAA for everymonitoring location is ≤0.060 mg/L forTTHM and ≤0.045 mg/L for HAA5.

(3) Compliance Requirements.

(A) General Requirements. 1. Where compliance is based on a loca-

tional running annual average (LRAA) orrunning annual average (RAA) of monthly orquarterly samples or averages and the systemfails to monitor for TTHM, HAA5, or bro-mate, this failure to monitor will be treated asa monitoring violation for the entire periodcovered by the annual average.

2. Where compliance is based on a run-ning annual average of monthly or quarterlysamples or averages and the system’s failureto monitor makes it impossible to determinecompliance with MRDLs for chlorine andchloramines, this failure to monitor will betreated as a monitoring violation for theentire period covered by the annual average.

3. All samples taken and analyzed underthe provisions of this rule must be included indetermining compliance, even if that numberis greater than the minimum required.

4. If, during the first year of monitoring,any individual quarter’s average will causethe running annual average of that system toexceed the MCL, the system is out of com-pliance at the end of that quarter.

5. Systems required to monitor quarter-ly. To comply with MCLs in paragraph 10CSR 60-4.094(2)(C)1.the system must calcu-late LRAAs for TTHM and HAA5 usingmonitoring results collected under this ruleand determine that each LRAA does notexceed the MCL. If the system fails to com-plete four (4) consecutive quarters of moni-toring, the system must calculate compliancewith the MCL based on the average of theavailable data from the most recent four (4)quarters. If the system takes more than one(1) sample per quarter at a monitoring loca-tion, the system must average all samplestaken in the quarter at that location to deter-mine a quarterly average to be used in theLRAA calculation.

6. Systems required to monitor yearly orless frequently. To determine compliancewith the Stage 2 D/DBP MCLs in subpara-graph 10 CSR 60-4.094(3)(D)3.A., the sys-tem must determine that each sample taken isless than the MCL. If any sample exceeds theMCL, the system must comply with therequirements of increased monitoring of thisrule. If no sample exceeds the MCL, thesample result for each monitoring location isconsidered the LRAA for that monitoringlocation.

7. Violation. If a system fails to monitor,the system is in violation of the monitoringrequirements for each quarter or monitoringperiod that a monitoring result would be usedin calculating a LRAA for TTHM and HAA5or RAA for bromate or chlorite.

(B) Disinfectant Residuals, Chlorite, and

Bromate. 1. Chlorine and chloramines.

A. Compliance must be based on arunning annual arithmetic average, computedquarterly, of monthly averages of all samplescollected by the system under paragraph(2)(A)1. of this rule. If the average coveringany consecutive four (4)-quarter periodexceeds the MRDL, the system is in violationof the MRDL and must notify the public pur-suant to 10 CSR 60-8.010, in addition toreporting to the department pursuant to 10CSR 60-7.010.

B. In cases where systems switchbetween the use of chlorine and chloraminesfor residual disinfection during the year,compliance must be determined by includingtogether all monitoring results of both chlo-rine and chloramines in calculating compli-ance. Reports submitted pursuant to 10 CSR60-7.010(5) must clearly indicate whichresidual disinfectant was analyzed for eachsample.

2. Chlorine dioxide. A. Acute violations. Compliance

must be based on consecutive daily samplescollected by the system under subparagraph(2)(A)2.A. of this rule. If any daily sampletaken at the entrance to the distribution sys-tem exceeds the MRDL, and on the followingday one (1) (or more) of the three (3) samplestaken in the distribution system exceed theMRDL, the system is in violation of theMRDL and must take immediate correctiveaction to lower the level of chlorine dioxidebelow the MRDL and must notify the publicpursuant to the procedures for acute healthrisks in 10 CSR 60-8.010(2), in addition toreporting to the department pursuant to 10CSR 60-7.010. Failure to take samples in thedistribution system the day following anexceedance of the chlorine dioxide MRDL atthe entrance to the distribution system willalso be considered an MRDL violation andthe system must notify the public of the vio-lation in accordance with the provisions foracute violations under 10 CSR 60-8.010(2), inaddition to reporting to the department pur-suant to 10 CSR 60-7.010.

B. Nonacute violations. Compliancemust be based on consecutive daily samplescollected by the system in compliance withthis rule.

(I) If any two (2) consecutive dailysamples taken at the entrance to the distribu-tion system detect chlorine dioxide, the sys-tem must take corrective action to lower thechlorine dioxide level.

(II) If any two (2) consecutive dailysamples taken at the entrance to the distribu-tion system exceed the MRDL and all distri-bution system samples taken are below the


Secretary of State


MRDL, the system is in violation of theMRDL and must take corrective action tolower the level of chlorine dioxide below theMRDL at the point of sampling and notifythe public pursuant to the procedures fornonacute health risks in 10 CSR 60-8.010(3),in addition to reporting to the departmentpursuant to 10 CSR 60-7.010. Failure to mon-itor at the entrance to the distribution systemthe day following an exceedance of the chlo-rine dioxide MRDL at the entrance to the dis-tribution system is also an MRDL violationand the system must notify the public of theviolation in accordance with the provisionsfor nonacute violations in 10 CSR 60-8.010(3), in addition to reporting to thedepartment pursuant to 10 CSR 60-7.010.

(C) Disinfection Byproduct Precursors(DBPP).

1. Systems using surface water orground water under the direct influence ofsurface water and using conventional filtra-tion treatment must operate with enhancedcoagulation or enhanced softening to achievethe TOC percent removal levels specified inthis rule unless the system meets at least one(1) of the alternative compliance criteria list-ed here. These systems must still complywith monitoring and compliance require-ments of this rule. The alternative compliancecriteria for enhanced coagulation andenhanced softening are:

A. The system’s source water TOClevel, measured according to 10 CSR 60-5.010, is less than 2.0 mg/L, calculated quar-terly as a running annual average;

B. The system’s treated water TOClevel, measured according to 10 CSR 60-5.010, is less than 2.0 mg/L, calculated quar-terly as a running annual average;

C. The system’s source water TOClevel, measured according to 10 CSR 60-5.010, is less than 4.0 mg/L, calculated quar-terly as a running annual average; the sourcewater alkalinity, measured according to 10CSR 60-5.010, is greater than sixty (60)mg/L (as CaCO3), calculated quarterly as arunning annual average; and either theTTHM and HAA5 running annual averagesare no greater than 0.040 mg/L and 0.030mg/L, respectively; or prior to the effectivedate for compliance with this rule, the systemhas made a clear and irrevocable financialcommitment not later than the effective datefor compliance with this rule to use technolo-gies that will limit the levels of TTHMs andHAA5 to no more than 0.040 mg/L and0.030 mg/L, respectively. Systems must sub-mit evidence of a clear and irrevocable finan-cial commitment, in addition to a schedulecontaining milestones and periodic progressreports for installation and operation of

appropriate technologies, to the departmentfor approval not later than the effective datefor compliance with this rule. These tech-nologies must be installed and operating notlater than June 30, 2005. Failure to installand operate these technologies by the date inthe approved schedule will constitute a viola-tion;

D. The TTHM and HAA5 runningannual averages are no greater than 0.040mg/L and 0.030 mg/L, respectively, and thesystem uses only chlorine for primary disin-fection and maintenance of a residual in thedistribution system;

E. The system’s source water SUVA,prior to any treatment and measured monthlyaccording to 10 CSR 60-5.010, is less than orequal to 2.0 L/mg-m, calculated quarterly asa running annual average. SUVA refers toSpecific Ultraviolet Absorption at two hun-dred fifty-four nanometers (254 nm), an indi-cator of the humic content of water. It is acalculated parameter obtained by dividing asample’s ultraviolet absorption at a wave-length of 254 nm (UV254) (in m=1) by its con-centration of dissolved organic carbon (DOC)(in mg/L); and

F. The system’s finished water SUVA,measured monthly according to 10 CSR 60-5.010, is less than or equal to 2.0 L/mg-m,calculated quarterly as a running annual aver-age.

2. Additional alternative compliance cri-teria for softening systems. Systems practic-ing enhanced softening that cannot achievethe Step 1 TOC removals may use the alter-native compliance criteria listed here in lieuof complying with paragraph (3)(C)3. of thisrule. Systems must still comply with moni-toring and compliance requirements of thisrule.

A. Softening that results in loweringthe treated water alkalinity to less than sixty(60) mg/L (as CaCO3), measured monthlyaccording to 10 CSR 60-5.010 and calculatedquarterly as a running annual average.

B. Softening that results in removingat least ten (10) mg/L of magnesium hardness(as CaCO3), measured monthly according to10 CSR 60-5.010 and calculated quarterly asan annual running average.

3. Enhanced coagulation and enhancedsoftening performance requirements.

A. Systems must achieve the percentreduction of TOC specified in Table 1between the source water and the combinedfilter effluent, unless the departmentapproves a system’s request for alternate min-imum TOC removal (Step 2) requirements.Systems may begin monitoring to determinewhether Step 1 TOC removals can be mettwelve (12) months prior to the compliance

date for the system. This monitoring is notrequired and failure to monitor during thisperiod is not a violation. However, any sys-tem that does not monitor during this period,and then determines in the first twelve (12)months after the compliance date that it is notable to meet the Step 1 requirements andmust therefore apply for alternate minimumTOC removal (Step 2) requirements, is noteligible for retroactive approval of alternateminimum TOC removal (Step 2) require-ments and is in violation. Systems may applyfor alternate minimum TOC removal (Step 2)requirements any time after the compliancedate. For systems required to meet Step 1TOC removals, if the value calculated underpart (3)(C)4.A.(IV) of this rule is less than1.00, the system is in violation of the treat-ment technique requirements and must notifythe public pursuant to 10 CSR 60-8.010 inaddition to reporting to the department pur-suant to 10 CSR 60-7.010.

B. Required Step 1 TOC reductions,indicated in the following table, are basedupon specified source water parameters mea-sured in accordance with 10 CSR 60-5.010.Systems practicing softening are required tomeet the Step 1 TOC reductions in the farright column (Source water alkalinity >120mg/L) for the specified source water TOC.

1Systems meeting at least one (1) of the con-ditions in paragraph (3)(C)1. of this rule arenot required to operate with enhanced coagu-lation. 2Softening systems meeting one (1) of thealternative compliance criteria in paragraph(3)(C)1. of this rule are not required to oper-ate with enhanced softening. 3Systems practicing softening must meet theTOC removal requirements in this column.

C. Conventional treatment systemsusing surface water or ground water under thedirect influence of surface water that cannotachieve the Step 1 TOC removals due to waterquality parameters or operational constraintsmust apply to the department, within three (3)months of failure to achieve the Step 1 TOCremovals, for approval of alternative minimumTOC removal (Step 2) requirements submittedby the system. If the department approves thealternative minimum TOC removal (Step 2)requirements, the department may make thoserequirements retroactive for the purposes of



determining compliance. Until the depart-ment approves the alternate minimum TOCremoval (Step 2) requirements, the systemmust meet the Step 1 TOC removals.

D. Alternate minimum TOC removal(Step 2) requirements. Applications made tothe department by enhanced coagulation sys-tems for approval of alternative minimumTOC removal (Step 2) requirements undersubparagraph (3)(C)3.C. of this rule mustinclude, as a minimum, results of bench- orpilot-scale testing conducted under this sub-paragraph (3)(C)3.D. and used to determinethe alternate enhanced coagulation level.

(I) Alternate enhanced coagulationlevel is defined as coagulation at a coagulantdose and pH as determined by the methoddescribed here such that an incremental addi-tion of ten (10) mg/L of alum (or equivalentamount of ferric salt) results in a TOCremoval of less than or equal to 0.3 mg/L.The percent removal of TOC at this point onthe “TOC removal versus coagulant dose”curve is then defined as the minimum TOCremoval required for the system. Onceapproved by the department, this minimumrequirement supersedes the minimum TOCremoval required by Table 1 of this rule. Thisrequirement will be effective until such timeas the department approves a new value basedon the results of a new bench- and pilot-scaletest. Failure to achieve department-set alter-native minimum TOC removal levels is a vio-lation.

(II) Bench- or pilot-scale testing ofenhanced coagulation must be conducted byusing representative water samples andadding 10 mg/L increments of alum (orequivalent amounts of ferric salt) until the pHis reduced to a level less than or equal to theenhanced coagulation Step 2 target pH shownin Table 2.

(III) For waters with alkalinities ofless than sixty (60) mg/L for which additionof small amounts of alum or equivalent addi-tion of iron coagulant drives the pH below5.5 before significant TOC removal occurs,the system must add necessary chemicals tomaintain the pH between 5.3 and 5.7 in sam-ples until the TOC removal of 0.3 mg/L per10 mg/L alum added (or equivalent additionof iron coagulant) is reached.

(IV) The system may operate at anycoagulant dose or pH necessary (consistentwith other regulatory requirements) toachieve the minimum TOC percent removalapproved under subparagraph (3)(C)3.C. ofthis rule.

(V) If the TOC removal is consis-tently less than 0.3 mg/L of TOC per 10mg/L of incremental alum dose at all dosagesof alum (or equivalent addition of iron coag-ulant), the water is deemed to contain TOCnot amenable to enhanced coagulation. Thesystem may then apply to the department fora waiver of enhanced coagulation require-ments.

4. Compliance calculations.A. Systems using surface water or

ground water under the direct influence ofsurface water, other than those identified inparagraphs (3)(C)1. or (3)(C)2. of this rule,must comply with requirements contained insubparagraphs (3)(C)3.B. or (3)(C)3.C. ofthis rule. Systems must calculate compliancequarterly, beginning after the system has col-lected twelve (12) months of data, by deter-mining an annual average using the followingmethod:

(I) Determine actual monthly TOCpercent removal, equal to: (1 – (treated waterTOC/source water TOC)) × 100;

(II) Determine the required month-ly TOC percent removal;

(III) Divide the value in part(3)(C)4.A.(I) by the value in part(3)(C)4.A.(II); and

(IV) Add together the results ofpart (3)(C)4.A.(III) for the last twelve (12)months and divide by twelve (12). If the valuecalculated is less than 1.00, the system is notin compliance with the TOC percent removalrequirements.

B. Systems may use the following pro-visions in lieu of the calculations in subpara-graph (3)(C)4.A. of this rule to determinecompliance with TOC percent removalrequirements:

(I) In any month that the system’streated or source water TOC level, measuredaccording to 10 CSR 60-5.010, is less than2.0 mg/L, the system may assign a monthlyvalue of 1.0 (in lieu of the value calculated inpart (3)(C)4.A.(III) of this rule);

(II) In any month that a systempracticing softening removes at least 10 mg/Lof magnesium hardness (as CaCO3), the sys-tem may assign a monthly value of 1.0 (inlieu of the value calculated in part(3)(C)4.A.(III) of this rule);

(III) In any month that the system’ssource water SUVA, prior to any treatmentand measured according to 10 CSR 60-5.010,is less than or equal to 2.0 L/mg-m, the sys-

tem may assign a monthly value of 1.0 (inlieu of the value calculated in part(3)(C)4.A.(III) of this rule);

(IV) In any month that the system’sfinished water SUVA, measured according to10 CSR 60-5.010, is less than or equal to 2.0L/mg-m, the system may assign a monthlyvalue of 1.0 (in lieu of the value calculated inpart (3)(C)4.A.(III) of this rule); and

(V) In any month that a systempracticing enhanced softening lowers alkalin-ity below sixty (60) mg/L (as CaCO3), thesystem may assign a monthly value of 1.0 (inlieu of the value calculated in part(3)(C)4.A.(III) of this rule).

C. Systems using conventional treat-ment and surface water or ground waterunder the direct influence of surface watermay also comply with the requirements ofthis rule by meeting the criteria in paragraphs(3)(C)1. or (3)(C)2. of this rule.

(D) Disinfection Byproducts. 1. Bromate. Compliance must be based

on a running annual arithmetic average, com-puted quarterly, of monthly samples (or, formonths in which the system takes more thanone sample, the average of all samples takenduring the month) collected by the system asprescribed by paragraph (2)(A)4. of this rule.If the average of samples covering any con-secutive four-quarter period exceeds theMCL, the system is in violation of the MCLand must notify the public pursuant to 10CSR 60-8.010, in addition to reporting to thedepartment pursuant to 10 CSR 60-7.010. If aPWS fails to complete twelve (12) consecu-tive months’ monitoring, compliance with theMCL for the last four (4)-quarter complianceperiod must be based on an average of theavailable data.

2. Chlorite. Compliance must be basedon an arithmetic average of each three (3)sample set taken in the distribution system asprescribed by item (2)(A)3.C.(II) and sub-paragraph (2)(A)3.B. of this rule. If the arith-metic average of any three (3) sample setexceeds the MCL, the system is in violationof the MCL and must notify the public pur-suant to 10 CSR 60-8.010, in addition toreporting to the department pursuant to 10CSR 60-7.010.

3. Total Trihalomethane (TTHM) andHaloacetic Acid (HAA).

A. Stage 2 Disinfectants/DisinfectionByproducts—Locational Running AnnualAverage (LRAA) Compliance. The MCLs of0.080 mg/L for TTHM and 0.060 mg/L forHAA5 must be complied with as a locationalrunning annual average at each monitoringlocation.

B. If the system is required to conductquarterly monitoring, the system must make


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compliance calculations at the end of thefourth calendar quarter that follows the com-pliance date and at the end of each subse-quent quarter (or earlier if the LRAA calcu-lated based on fewer than four (4) quarters ofdata would cause the MCL to be exceededregardless of the monitoring results of subse-quent quarters). If the system is required toconduct monitoring at a frequency that is lessthan quarterly, the system must make compli-ance calculations beginning with the firstcompliance sample taken after the compli-ance date.

C. The department may determinethat the combined distribution system doesnot include certain consecutive systems basedon factors such as receiving water from awholesale system only on an emergency basisor receiving only a small percentage andsmall volume of water from a wholesale sys-tem. The department may also determine thatthe combined distribution system does notinclude certain wholesale systems based onfactors such as delivering water to a consecu-tive system only on an emergency basis ordelivering only a small percentage and smallvolume of water to a consecutive system.

(E) Operational Evaluation Levels. 1. The system has exceeded the opera-

tional evaluation level at any monitoring loca-tion where the sum of the two (2) previousquarters of TTHM results plus twice the cur-rent quarter’s TTHM result, divided by four(4) to determine an average, exceeds 0.080mg/L, or where the sum of the two (2) previ-ous quarters of HAA5 results plus twice thecurrent quarter’s HAA5 result, divided byfour (4) to determine an average, exceeds0.060 mg/L.

2. If Operational Evaluation Levels areExceeded.

A. If the system exceeds the opera-tional evaluation level, the system must con-duct an operational evaluation and submit awritten report of the evaluation to the depart-ment no later than ninety (90) days afterbeing notified of the analytical result thatcauses the system to exceed the operationalevaluation level. The written report must bemade available to the public upon request.

B. The system’s operational evalua-tion must include an examination of systemtreatment and distribution operational prac-tices, including storage tank operations,excess storage capacity, distribution systemflushing, changes in sources or source waterquality, and treatment changes or problemsthat may contribute to TTHM and HAA5 for-mation and what steps could be considered tominimize future exceedences.

(I) The system may request and thedepartment may allow a limit to the scope of

the evaluation if the system is able to identifythe cause of the operational evaluation levelexceedance.

(II) The system’s request to limitthe scope of the evaluation does not extendthe schedule in subparagraph (3)(E)2.A. ofthis rule for submitting the written report.The department must approve this limitedscope of evaluation in writing, and the systemmust keep that approval with the completedreport.

(F) Stage 2 D/DBP Reporting and Record-Keeping Requirements.

1. Reporting requirements are found in10 CSR 60-7.010, Reporting Requirements.

2. Record-keeping requirements arefound in 10 CSR 60-9.010, Requirements forMaintaining Public Water System Records.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed Feb. 27, 2009, effectiveOct. 30, 2009. Amended: Filed June 13,2018, effective Feb. 28, 2019.


10 CSR 60-4.100 Maximum VolatileOrganic Chemical Contaminant Levels andMonitoring Requirements

PURPOSE: This rule establishes maximumcontaminant levels and monitoring require-ments for volatile organic chemicals.

(1) This rule applies to community and non-transient noncommunity public water sys-tems.

(2) The following are the maximum contami-nant levels (MCLs) for volatile organic chem-icals (VOCs).

MaximumContaminant Level,

MilligramsContaminant Per Liter(A) Eight (8) original VOCs

1. Benzene 0.005 2. Carbon tetrachloride 0.0053. 1,2-dichloroethane 0.0054. 1,1-dichloroethylene 0.0075. para-dichlorobenzene 0.0756. 1,1,1-trichloroethane 0.27. Trichloroethylene 0.0058. Vinyl chloride 0.002

MaximumContaminant Level,

MilligramsContaminant Per Liter(B) Thirteen (13) VOCs

1. cis-1,2-dichloroethylene 0.07

2. Dichloromethane 0.0053. 1,2-dichloropropane 0.0054. Ethylbenzene 0.75. Monochlorobenzene 0.16. o-dichlorobenzene 0.67. Styrene 0.18. Tetrachloroethylene 0.0059. Toluene 110. 1,2,4-Trichlorobenzene 0.07 11. 1,1,2-Trichloroethane 0.00512. trans-1,2-

dichloroethylene 0.113. Xylenes (total) 10

(3) For the purpose of determining compli-ance with MCLs, a supplier of water mustcollect samples of the product water for anal-yses as follows:

(A) During the initial three (3)-year com-pliance, all community and nontransient non-community water systems must collect an ini-tial round of four (4) consecutive quarterlysamples for each of the contaminants listed insection (2) unless a waiver has been grantedby the department. The department will des-ignate the year in which each system sampleswithin this compliance period;

(B) All public water systems shall sampleat points in the distribution system represen-tative of each water source or at each entrypoint to the distribution system. Each samplemust be taken at the same sampling point,unless conditions make another samplingpoint more representative of each source ortreatment plant. The sampling point will beafter the application of treatment, if any;

(C) If the system draws water from morethan one (1) source and the sources are com-bined before distribution, the system mustsample at an entry point to the distributionsystem during periods of normal operatingconditions;

(D) The department may require more fre-quent monitoring than specified in subsection(3)(A) of this rule and may require confirma-tion samples for positive and negative resultsat its discretion; and

(E) If one (1) sampling point is in violationof an MCL, the system is in violation of theMCL.

1. For systems monitoring more thanonce per year, compliance with the MCL isdetermined by a running annual average ateach sampling point.

2. Systems monitoring annually or lessfrequently whose sample result exceeds theMCL must begin quarterly sampling. Thesystem will not be considered in violation ofthe MCL until it has completed one (1) yearof quarterly sampling.

3. If any sample result will cause therunning annual average to exceed the MCL at



any sampling point, the system is out of com-pliance with the MCL immediately.

4. If a system fails to collect the requirednumber of samples, compliance will be basedon the total number of samples collected.

5. If a sample result is less than thedetection limit, zero will be used to calculatethe annual average.

(4) If contaminants are not detected duringthe first three (3)-year compliance period,systems may decrease their sampling frequen-cy beginning in the next year.

(A) Groundwater systems must sampleannually. After three (3) years of annual sam-pling and no previous detection, groundwatersystems may reduce their sampling frequencyto one (1) sample per compliance period.

(B) Surface water systems must sampleannually after the initial sampling period ifthere are no contaminants detected in the ini-tial sampling.

(5) If contaminants are detected in any sam-ple, then systems must sample quarterlybeginning in the next quarter at each sam-pling point which resulted in a detection.

(A) Groundwater systems must sample aminimum of two (2) quarters and surfacewater systems must sample a minimum offour (4) quarters to establish a baseline.

(B) If the MCL is exceeded, as described insubsection (5)(E) or (F) of this rule, then sys-tems must sample quarterly beginning in thenext quarter. Systems must sample a minimumof four (4) quarters to establish a baseline.

(C) If the baseline indicates a system’s ana-lytical results are reliably and consistentlybelow the MCL, the department may reducethe system’s sampling frequency to annually.(Annual sampling must be conducted duringthe quarter which previously yielded thehighest analytical result.)

(D) Systems which have three (3) consecu-tive annual samples with no detection of acontaminant may apply to the department fora waiver.

(E) If a system conducts sampling morefrequently than annually, the system will bein violation when the running annual averageat any sampling point exceeds the MCL.

(F) If a system conducts sampling annual-ly or on a less frequent basis, the system willbe in violation when one (1) sample (or theaverage of the initial and confirmation sam-ples) at any sampling point exceeds the MCL.

(6) A public water system may apply to thedepartment for susceptibility waivers fromrequired sampling. Systems are eligible forreduced monitoring in the initial three (3)-year compliance period. Waivers are effective

for two (2) compliance periods. The waivermust be renewed in subsequent complianceperiods, or the system must conduct samplingas required by section (3) of this rule. A pub-lic water system may apply to the departmentfor susceptibility waivers for reduced moni-toring contingent on the conduct of a thor-ough vulnerability assessment as required by10 CSR 60-6.060(3).

(A) As a condition of the susceptibilitywaiver, a groundwater system must take one(1) sample at each sampling point during thetime the waiver is effective (that is, one (1)sample during two (2) compliance periods orsix (6) years) and update its vulnerabilityassessment by the end of the first complianceperiod. The department must confirm that thesystem is not vulnerable.

(B) Surface water systems must sample ata frequency determined by the department. Avulnerability assessment according to 10 CSR60-6.060(3) must be required in subsequentcompliance periods in order for the system toreturn to its nonvulnerable status.

(C) For the purposes of this section, detec-tion is defined as greater than 0.0005 mg/L.

(7) As determined by the department, confir-mation samples may be required for eitherpositive or negative results. If a confirmationsample is used, the compliance determinationis based on the average of the results of boththe confirmation sample and the initial sam-ple.

(8) All new systems or systems that use a newsource of water that begin operation afterJanuary 22, 2004 must demonstrate compli-ance with the MCL or treatment techniquewithin a period of time specified by thedepartment. The system must also complywith the initial sampling frequencies speci-fied by the department to ensure a system candemonstrate compliance with the MCL ortreatment technique. Routine and increasedmonitoring frequencies shall be conducted inaccordance with the requirements in this rule.

AUTHORITY: section 640.100, RSMo 2016.*Original rule filed June 2, 1988, effectiveAug. 31, 1988. Rescinded and readopted:Filed March 31, 1992, effective Dec. 3, 1992.Amended: Filed May 4, 1993, effective Jan.13, 1994. Amended: Filed Feb. 1, 1996,effective Oct. 30, 1996. Amended: FiledMarch 17, 2003, effective Nov. 30, 2003.Amended: Filed June 13, 2018, effective Feb.28, 2019.


10 CSR 60-4.110 Special Monitoring forUnregulated Chemicals(Rescinded September 30, 2018)

AUTHORITY: section 640.100, RSMo 1994.Original rule filed June 2, 1988, effectiveAug. 31, 1988. Rescinded and readopted:Filed March 31, 1992, effective Dec. 3, 1992.Amended: Filed May 4, 1993, effective Jan.13, 1994. Amended: Filed Feb. 1, 1996,effective Oct. 30, 1996. Rescinded: FiledDec. 29, 2017, effective Sept. 30, 2018.


Secretary of State


rules of department of natural resources · 2019-01-28 · 10 csr 60-4.022 revised total coliform...

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