article 13 cross-connection control and backflow …
TRANSCRIPT
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ARTICLE 13
CROSS-CONNECTION CONTROL
AND BACKFLOW PREVENTION
TABLE OF CONTENTS
Page Number
SECTION 13-100 DEFINITIONS 13-3
SECTION 13-200 PURPOSE 13-13
13-210 CROSS CONNECTIONS 13-13
13-220 REQUIRED BACKFLOW PROTECTION 13-14
13-230 LOCATION OF BACKFLOW PREVENTION DEVICES 13-15
13-240 TYPES OF BACKFLOW PROTECTION
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13-240.1 Air Gaps 13-17
13-240.2 Vacuum Breakers 13-18
13-240.3 Double Check Valve Assembly 13-18
13-240.4 Reduced Pressure Zone Assembly
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13-240.5 Specialty Backflow Preventers 13-19
13-250 FIRE SERVICE SYSTEMS 13-20
13-260 SYSTEM AND DEVICE REQUIREMENTS 13-21
13-260.1 Identification of Potable and Non-Potable Water 13-21
13-260.2 Approved Backflow Prevention Devices 13-21
13-260.3 Prohibited Interconnections and Devices 13-22
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13-260.4 Backflow Prevention Device Installation 13-22
13-260.5 Shut-Off Valve Requirements 13-26
13-260.6 Irrigation Systems 13-26
13-260.7 Bypass Arrangements 13-27
13-260.8 Redundant Backflow Prevention Device Requirements 13-27
13-260.9 Air Gap Criteria 13-28
13-260.10 Heat Transfer Systems 13-28
13-260.11 Bottom Feed Hot Water Tanks 13-29
13-270 MAINTENANCE OF BACKFLOW PREVENTION DEVICES 13-29
13-270.1 Inspection 13-29
13-270.2 Testing 13-30
13-270.2.1 Test Procedures 13-31
13-270.2.2 Test Records 13-31
13-270.2.3 Tester Certification 13-32
13-270.3 Maintenance 13-32
Table 13-1 SUMMARY OF BACKFLOW PREVENTION DEVICE
REQUIREMENTS 13-33
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ARTICLE 13
CROSS-CONNECTION CONTROL
AND BACKFLOW PREVENTION
SECTION 13-100 DEFINITIONS
AIR GAP SEPARATION: The unobstructed vertical distance through the free
atmosphere between the lowest opening from any pipe, faucet, or outlet supplying
potable water to a tank, plumbing fixture, appliance, vessel, or other device, and
the flood level rim of the receptacle. An "Approved Air Gap Separation" shall be at
least double the diameter of the supply pipe measured vertically above the
overflow rim of the tank, plumbing fixture, assembly, appliance, vessel or other
device, and in no case shall be less than one (1) inch.
ASSE: The American Society of Sanitary Engineering. An association of
plumbing professionals, engineers, and technicians that publishes performance
standards and technical guidelines for the plumbing industry. The ASSE
publishes, quarterly, a listing of the backflow prevention devices that have been
approved for use after extensive testing under controlled conditions.
ATMOSPHERIC VACUUM BREAKER: A device manufactured specifically to
prevent back-siphonage by creating an atmospheric vent when there is a negative
pressure or sub-atmospheric pressure in a water supply line. The device consists
of a float check valve and an air inlet port. The device may be equipped with an
integral shutoff valve located immediately upstream. The device must comply with
and be approved under ASSE Standard 1001.
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AUXILIARY WATER SYSTEM: Any water supply, system, or approved public
water system available as a supplement to another water supply, system or
approved public water system. Auxiliary waters may include water from another
purveyors' public potable water system or any natural source(s) such as a well,
spring, river, stream, pond, etc., or "used waters" or industrial fluids. The auxiliary
waters may be polluted or contaminated or may be objectionable and constitute an
unacceptable water source over which the water purveyor does not have sanitary
control.
AWWA: The American Water Works Association. An organization of water
quality professionals, engineers, scientists, managers, and operators that
publishes performance standards and technical guidelines used throughout the
water industry.
BACKFLOW: The reversal of the normal flow of water caused by either back
pressure or back-siphonage that may introduce contaminants, pollutants, process
fluids, used water, untreated waters, chemicals, gases, other non-potable waters,
or another purveyor's public potable water into any part of the waterworks.
BACKFLOW PREVENTION DEVICE: Any "approved" device, method, or type of
construction designed and manufactured specifically to prevent backflow into a
waterworks.
BACKFLOW PREVENTION DEVICE WORKER: An individual who holds a valid
Tradesman Certificate as a “Backflow Prevention Device Worker” issued by the
Board for Contractors, Department of Professional and Occupational Regulation,
Commonwealth of Virginia, and a valid “Backflow Prevention Device Worker”
registration card issued by the City.
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BACK PRESSURE: A positive pressure placed on any downstream component of
a waterworks or consumer’s water system relative to any upstream pressure.
BACK-SIPHONAGE: A form of backflow due to a negative or sub-atmospheric
pressure within a waterworks or a consumer’s water system.
CITY: A representative of the government of the City of Manassas, including but
not limited to, the Inspections/Fire Marshal’s Office and/or the Water and Sewer
Division, that have responsibility for enforcement of the applicable provisions of the
Uniform Statewide Building Code, the Virginia Waterworks Regulations, and the
Code of Ordinances, City of Manassas, Virginia.
CONSUMER: The operator, manager, tenant, or property owner responsible for
and/or in control of a premise or premises supplied by or in any manner connected
to the waterworks.
CONSUMER'S WATER SYSTEM: Any water system located on the consumer's
premises downstream of the water meter and supplied by or in any manner
connected to the waterworks.
CONTAINMENT: A method of protecting the waterworks from potential backflow
of pollutants or contaminants by the installation of a backflow prevention device in
the potable water service line, at or directly after the meter but prior to any other
service tees or take-offs.
CONTAMINATION: Any introduction into the waterworks of micro-organisms,
wastes, and/or sewage, wastewater, undesirable chemicals, industrial fluids,
process fluids, materials, compounds, or gases which create an actual or potential
hazard to the waterworks, the consumer’s water system, and the public health.
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CROSS-CONNECTION: Any existing or potential connection or structural
arrangement, direct or indirect, to or between the waterworks and/or the
consumer’s water system and a source of contamination or pollution.
DEGREE OF HAZARD: A ranking or level of danger to the consumer’s water
system, the waterworks, or the public health posed by a particular substance or set
of circumstances if backflow were to occur.
DOUBLE CHECK VALVE ASSEMBLY: A backflow prevention device consisting
of two (2) single, independently acting check valves, a tightly closing shut-off valve
located at each end of the assembly, and petcocks for connecting hoses from an
instrument used for testing the tightness of each check valve. The device must
comply with and be approved under ASSE Standard 1015.
DUAL CHECK ASSEMBLY: A backflow prevention device consisting of two (2)
check valves that are internally loaded or biased to a normally closed position.
The check valves open only when there is forward flow. The device is used for low
hazard applications only and must comply with and be approved under ASSE
Standard 1024.
DUAL CHECK WITH INTERMEDIATE ATMOSPHERIC VENT: A backflow
prevention device consisting of two (2) independently operating check valves and
an air vent valve located between the two checks. The device may be used under
continuous pressure. However, it shall only be used in low or atmospheric
pressure conditions and must comply with and be approved under ASSE Standard
1012.
FIRE SERVICE MAIN: A service main that is connected at a street valve located
on the public water line and terminates at the base of sprinkler riser. This fire
service main usually has a Post Indicator Valve attached in-line (free standing or
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attached adjacent to bottom of sprinkler riser). This service line is always privately
owned and maintained.
FCCCHR/USC: The Foundation for Cross-Connection Control and Hydraulics
Research, University of Southern California. An organization developed by an
institution of higher education to set and promote standards for cross-connection
control and backflow prevention. The organization ensures conformance with
applicable standards, provides education for industry professionals, produces
technical references and guidelines, and publishes, quarterly, a list of backflow
prevention devices that have been approved for use after extensive testing in a
controlled laboratory condition.
FLOOD LEVEL RIM: The top edge of a receptacle from which water may
overflow. The flood level rim does not take into consideration an overflow outlet, if
any, internal to the receptacle.
HEALTH HAZARD: An existing or potential threat of contamination to the
waterworks or the consumer’s water system of a physical or toxic nature that
constitutes a danger to public health.
HOSE CONNECTION VACUUM BREAKER (HCVB): A backflow prevention
device consisting of two (2) force-loaded independent check valves with an
atmospheric vent located between the checks, and a means for attaching a garden
type hose on the discharge side of the device. The device protects against back-
siphonage only and must not be subjected to more than twelve (12) hours of
continuous pressure. The device must comply with and be approved under ASSE
Standard 1011.
ISOLATE OR ISOLATION: A method of protecting the waterworks and/or
consumer’s water system from potential backflow of pollutants or contaminants by
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the installation of a backflow prevention device in the water supply to individual
(point of use) applications, such as a boiler, sink, appliance, equipment item,
process, or system, connected to the consumer’s water system (typically on the
interior of a building) downstream of the City’s water meter.
INSPECTIONS/FIRE MARSHAL’S OFFICE: A division of the Department of
Public Works, City of Manassas, Virginia, responsible for the enforcement of the
Virginia Uniform Statewide Building Code, including, but not limited to, the
plumbing code, mechanical code, electrical code, fire prevention code, and life
safety code.
INTERCHANGEABLE CONNECTION: An arrangement or device that will allow
alternate but not simultaneous use of two (2) sources of water.
LAB FAUCET BACKFLOW DEVICE (LFBD): A backflow prevention device
consisting of two (2) check valves. The device is typically used as an add-on to a
laboratory faucet that can have a flexible hose that extends downward into a sink
and below the flood level rim. Technically, the device is a vacuum breaker and
must not be subjected to back pressure. The device may be used for high or low
hazard applications and must comply with and be approved under ASSE Standard
1035.
OUTLET: The open end of a water supply pipe, relief valve, or drain from which
water or other substances may be discharged.
PLUMBING HAZARD: An internal or plumbing type of cross-connection in a
consumer's potable water system.
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POINT OF USE: An end-point of a water supply pipe in a consumer’s water
system to a particular or specific system, equipment item, vessel, plumbing fixture,
appliance, receptacle, or water outlet.
POLLUTION: The presence of any foreign substance (chemical, physical,
radiological, or biological) in water that is likely to degrade its quality and represent
an unnecessary risk or impair the usefulness of the water.
POLLUTION HAZARD: An actual or potential threat to the physical properties of
the waterworks or to the consumer’s water system that would represent a
nuisance, be aesthetically objectionable, or could cause damage to the system or
its appurtenances but would not be dangerous to the public health.
PRESSURE VACUUM BREAKER: A backflow prevention device consisting of an
independently operating internally loaded check valve and an independently
operating air inlet valve located on the discharge side of the check valve, with
tightly closing resilient-seated shutoff valves attached at each end of the device.
The PVB shall include two (2) approved petcock valves for testing the device, and
must comply with and be approved under ASSE Standard 1020.
PROCESS FLUIDS: Any fluid or solution which may chemically, biologically, or
otherwise contaminate or pollute the waterworks or a consumer’s water system,
and which would represent a health, pollutional, plumbing, or system hazard if
backflow were to occur. This includes, but is not limited to:
A. Polluted or contaminated waters;
B. Process waters;
C. Used water originating from the waterworks which may have
deteriorated in sanitary quality;
D. Cooling waters;
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E. Contaminated natural waters taken from wells, ponds, lakes,
streams, or irrigation systems;
F. Chemicals in solution or suspension; and
G. Oils, gases, acids, alkalis, and other liquids, fluids, or gases used in
commercial, industrial, or other processes, or those used for
firefighting purposes.
POTABLE WATER: Water provided for human consumption and domestic use
that meets or exceeds the National Primary Drinking Water Standards (NPDWS)
promulgated by the United States Environmental Protection Agency (USEPA) and
enforced by the Virginia Department of Health (VDH).
PURIFIED WATER: This term may be used interchangeably with Potable Water.
However, purified water is, characteristically, water that is free of minerals,
nutrients, organic substances, toxic agents, and is typically used for medical and
manufacturing purposes.
REDUCED PRESSURE ZONE ASSEMBLY: A backflow prevention device
consisting of two (2) independently acting, spring-loaded check valves together
with a hydraulically operated mechanically independent pressure differential relief
valve located between the two (2) checks, and equipped with resilient-wedge,
tightly closing shutoff valves at each end of the assembly. The device provides the
highest mechanical degree of hazard protection, can be used for health and non-
health hazards, and must comply with and be approved under ASSE Standard
1013.
SERVICE CONNECTION: The terminal end of a service line from the waterworks.
If a City water meter is installed in the service line, then the service connection
shall mean the downstream end of the meter. If no meter is installed, as is typical
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to a fire service main, the terminal end of the service connection is at the City’s
water main, designated by the shut-off valve closest to the City’s water main.
SERVICE LINE: The pipe conveying potable water to the consumer’s water
system, from the tap at the City’s water main to the terminal end of the City’s water
meter.
SYSTEM HAZARD: An actual or potential threat of severe damage to the
waterworks and/or the consumer’s water system, but not dangerous to public
health.
TOXIC SUBSTANCE: Any substance, including raw sewage, which, when
introduced into the waterworks or a consumer’s water system, creates or may
create a danger to the public health.
USED WATER: Any water supplied from the waterworks to another waterworks or
a consumer's water system after it has passed through the service connection and
is no longer under the control of the water purveyor.
VACUUM: Pressure exerted in an enclosed space, such as a pipe, that is less
than atmospheric pressure.
VDH: The Virginia Department of Health, Office of Drinking Water.
WATER PURVEYOR: The owner and operator of the waterworks that provides
approved domestic drinking water to the public. The City of Manassas is the water
purveyor. The waterworks is managed and operated by the Water and Sewer
Division.
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WATER AND SEWER DIVISION: A Division of the Utilities Department
responsible for day-to-day operation and maintenance of the City’s water
production and distribution system, and the cross-connection control and backflow
prevention program in cooperation with the Inspections/Fire Marshal’s Office.
WATER SUPERVISOR: The consumer or a person designated by the consumer
to be in responsible charge of maintaining the consumer’s water system free from
cross-connections and other sanitary defects, as required by applicable
regulations, ordinances, and codes. A Backflow Prevention Device Worker many
not act as a Water Supervisor unless he is a full-time employee of the consumer
and has day-to-day responsibility for the installation, use, and/or maintenance of
pipelines and equipment on the consumer’s premises.
WATERWORKS: The City of Manassas water production and distribution system.
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SECTION 13-200 PURPOSE
The purpose of the standard for cross-connection control and backflow prevention
is as follows:
A. To protect the waterworks and the consumer’s water system from the possibility of
contamination or pollution through connections or structural arrangements with any
existing or potential source through which it may be possible to introduce into any
part of the waterworks or consumer’s water system any used water, industrial fluid,
gas, or substance other than the intended potable water with which the system is
supplied;
B. To promote the elimination or control of existing and potential cross-connections
between the consumer's water system(s), plumbing fixtures, and piping systems;
and
C. To provide standards, instructions, procedures, guidelines, and references for the
installation and maintenance of backflow prevention methods and devices in
accordance with Part II, Article 3, Waterworks Regulations, Department of Health,
Commonwealth of Virginia; the Virginia Uniform Statewide Building Code, and
Chapter 118, Division 5, Code of Ordinances, City of Manassas, Virginia.
13-210 CROSS-CONNECTIONS
No person shall install or maintain a water service connection as follows:
A. To any premise(s) whereby a cross-connection(s) to the waterworks exists
or has the potential to exist;
B. To any premise(s) whereby water from an auxiliary water system may enter
the waterworks; and
C. To any premise(s) whereby water from a non-potable pipe, plumbing fixture,
device, appliance, equipment item, appurtenance, or other non-potable
system may enter the waterworks, unless such cross-connection(s) is
properly protected by the installation and proper maintenance of an
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approved backflow prevention device as required by the applicable
regulations, ordinances, codes, and standards.
13-220 REQUIRED BACKFLOW PROTECTION
An approved backflow prevention device shall be installed in the potable water
service main to each new building intended for commercial or industrial use, and in all
new buildings four (4) or more stories in height, including residential. The backflow
prevention device shall be installed after the water meter but prior to any unprotected
take-offs. The purpose of this requirement is to protect the City’s water distribution
system from cross-connection hazards that may originate on a customer’s premises. In
addition to new construction, an approved backflow prevention device shall be installed in
the potable water service main to each existing building being renovated, remodeled or
otherwise altered, and in existing buildings, as follows:
A. To whereby, in the judgment of the City or the VDH, a health, pollution,
plumbing, or system hazard to the waterworks exists;
B. To whereby the following conditions exist:
1. Premises having an auxiliary water system unless such auxiliary
system is accepted by the City as an additional source and the
source is approved by the VDH;
2. Premises on which any substance is handled in such a manner as to
create an actual or potential hazard to the waterworks. This shall
include premises having sources or systems containing process
fluids or water originating from a waterworks which is not under the
control of the City;
3. Premises having internal cross-connections that, in the judgment of
the City or the VDH, may not be easily correctable, or that intricate
plumbing arrangements make it impracticable to determine if and
where cross-connections exist;
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4. Premises where, because of security requirements or other
prohibitions or restrictions, it is impossible or impractical to make a
complete cross-connection survey;
5. Premises having a repeated history of cross-connections being
established or re-established;
6. Premises having fire protection systems utilizing combinations of
sprinklers, fire loops, storage tanks, pumps, antifreeze or other
chemicals, with no storage or auxiliary water sources; and
7. Other premises specified or determined by the City or the VDH when
cause can be shown that a potential cross-connection hazard, not
included above, exists.
Premises having booster pumps connected to the waterworks shall be equipped
with a low pressure cut-off device to shut-off the booster pump in the event the pressure
in the waterworks were to drop to 10 psi.
An approved backflow prevention device shall be installed in the pipe(s) supplying
water to point-of-use applications (outlets, fixtures, receptacles, appliances, equipment,
etc.) to prevent and/or control the potential for contamination or pollution of the
waterworks and/or the consumer’s water system, and in accordance with the
requirements of this document and the applicable regulations, ordinances, and codes.
Also see Table 13-1, Summary of Backflow Prevention Device Requirements,.
13-230 LOCATION OF BACKFLOW PREVENTION DEVICES
An approved backflow prevention device shall be installed, for containment
purposes, on each service line to a consumer's water system serving, but not limited to,
the following types of facilities:
• Hospitals;
• Medical and dental clinics;
• Nursing homes and long-term care facilities;
• Mortuaries;
• Funeral homes;
• Laboratories;
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• Piers, docks, and waterfront facilities;
• Sewage treatment and stormwater collection, pumping, and storage facilities;
• Food and beverage processing plants;
• Chemical manufacturing and processing plants;
• Petroleum manufacturing, processing, storage and distribution plants and facilities;
• Metal plating industries;
• Car, truck and other vehicle washing facilities;
• Dry cleaners and laundry cleaning facilities;
• Facilities where radioactive materials are processed and used;
• Irrigation systems;
• Fire service systems;
• Buildings four (4) or more stories in height;
• Slaughter houses and poultry processing plants;
• Farms where the water is used for other than household purposes; and
• Other facilities specified by the City and/or the VDH when reasonable cause can be shown for a potential backflow or cross-connection hazard.
An approved backflow prevention device shall be installed on each plumbing
fixture, pipe, appliance, appurtenance, equipment item, or process in the consumer’s
water system, where, in the judgment of the City of VDH, an internal cross-connection
hazard exists, and as required by the applicable plumbing code adopted by the City. Also
see Table 13-1, Summary of Backflow Prevention Device Requirements.
13-240 TYPES OF BACKFLOW PROTECTION
The type of backflow protection required shall be dependent on the degree of
hazard which exists or has the potential to exist and shall be based on an assessment of
a structure, building, facility, equipment item, plumbing fixture, appliance, water service, or
outlet. The assessment shall determine the nature of the potential contaminant or
pollutant, the probability of backflow, and the potential effect on the waterworks and/or the
consumer’s water system. The minimum backflow protection methods and/or devices
required shall be as provided in Article 13 of this standard, and the applicable regulations,
ordinances, and codes. Also see Table 13-1, Summary of Backflow Prevention
Device Requirements.
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13-240.1 AIR GAPS
Air gaps (AG) provide the highest degree of protection. However, an AG is
not always practical and is the easiest backflow prevention method to circumvent,
rendering it ineffective. In particular situations, or under certain circumstances or
conditions, and at the discretion of the City or VDH, a mechanical backflow
prevention device may be required in addition to an AG.
Air gaps shall be installed and maintained as follows:
A. Between the vent outlet opening and a drain inlet on DC/IAV backflow
prevention devices. Where a drain pipe is installed to convey drainage
away from the device and its location, an AG is preferred between the
device’s outlet and the inlet of the drain pipe. An AG at this location
provides an observation point to determine leakage and potential failure of
the device. However, if an AG is not possible or practical at this location,
then an AG shall be installed between the outlet end of the drain pipe and
the inlet of any waste drain or other receptor.
B. Between the pressure relief valve outlet on RPZ backflow prevention
devices and the drain pipe inlet, if the device is installed indoors. The drain
pipe shall be installed to convey discharges from the device to an approved
waste drain or receptor. The drain pipe must be sized to handle the
maximum water output of the RPZ’s relief valve.
C. As a minimum, all AG shall be two and one-half (2½) times the diameter of
the backflow prevention devices vent or relief valve opening, and never less
than one-inch (1”).
Also see Table 13-1, Summary of Backflow Prevention Device
Requirements.
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13-240.2 VACUUM BREAKERS
There are two (2) basic types of vacuum breakers, the Atmospheric
Vacuum Breaker (AVB) and the Pressure Vacuum Breaker (PVB). However, there
are several variations of the vacuum breaker. Vacuum breakers protect against
back-siphonage only. The AVB is designed to provide protection only under
intermittent or short-term water supply pressure conditions. The PVB is designed
to provide protection under long-term or continuous water supply pressure
conditions. The AVB or PVB shall not be used if back pressure could develop in
the downstream piping.
Vacuum breakers are primarily used for non-health hazards. However, in
certain situations, conditions, or on specific equipment items, appliances, or
plumbing fixtures, vacuum breakers may be used to provide backflow protection
from health hazards. If used for health hazard applications (such as medical
facility plumbing fixtures or other similar equipment), an additional backflow
preventer may also be required, at the discretion of the City or the VDH. Also see
Table 13-1, Summary of Backflow Prevention Device Requirements.
13-240.3 DOUBLE CHECK VALVE ASSEMBLY
The Double Check Valve (DCV) assembly consists of two spring-loaded,
independently acting check valves. The DCV assembly is effective against
backflow caused by back pressure and back-siphonage and is used to protect the
waterworks or a consumer’s water system from pollutants that would not constitute
a health hazard but may be aesthetically objectionable. The DCV assembly shall
be used for low, non-health hazard applications only.
The DCV assembly is a valve that must be maintained regularly to ensure
positive protection. This includes operational testing, overhauling by
replacement of internal components, or replacement of the device at a frequency
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specified in applicable regulations, codes, ordinances, or standards. More
frequent testing may be required, at the discretion of the City or VDH. Also see
Table 13-1, Summary of Backflow Prevention Requirements.
13-240.4 REDUCED PRESSURE ZONE ASSEMBLY
The Reduced Pressure Zone (RPZ) assembly consists of two (2) spring-loaded
check valves with a hydraulically operating, mechanically independent pressure
differential relief valve located between the check valves and below the first check
valve. The RPZ is the most effective mechanical backflow prevention device. It
provides protection against back pressure and back-siphonage conditions, and health
and non-health hazards. The RPZ is a valve that must be maintained regularly to
ensure positive protection. This includes operational testing and overhaul by
replacement of internal components at a frequency specified in the applicable
regulations, codes, ordinances, or standards. More frequent testing may be required, at
the discretion of the City or VDH. Also see Table 13-1, Summary of Backflow
Prevention Device Requirements.
13-240.5 SPECIALTY BACKFLOW PREVENTERS
In certain situations and/or under particular circumstances or conditions, a
specialty type of backflow prevention device will be required to provide adequate
protection to the waterworks and/or the consumer’s water system from contamination or
pollution in the event backflow were to occur. The types of devices include, but are not
limited to, the following:
A. Dual Check Assembly (DC);
B. Dual Check with Intermediate Atmospheric Vent (DC/IAV);
C. Hose Connection Vacuum Breaker (HCVB); and
D. Laboratory Faucet Backflow Preventer (LFBD).
In addition to the above, other specialty types of backflow preventers may
be required, as follows:
A. Backflow Preventer for Carbonated Beverage Systems (ASSE
Standard 1022); and
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B. Dual Check Valve Type Backflow Preventer for Carbonated
Beverage Dispensers – Post Mix Type (ASSE Standard 1032).
The two devices above are manufactured specifically for carbonated beverage
systems, are stainless steel, and contain no copper components. Also see Table 13-1,
Summary of Backflow Prevention Device Requirements.
13-250 FIRE SERVICE SYSTEMS
An approved backflow prevention device shall be installed in the water service
main to all fire protection systems installed in new commercial and industrial use
buildings. The device must be located prior to the alarm check valve and the fire
department connection (FDC) or Siamese connection. The location and installation of the
backflow prevention device must be approved by the City Fire Marshal.
An approved Double Check Valve (DCV) assembly backflow prevention device
shall be installed, as a minimum. Where water from an auxiliary source such as a
storage tank, raw water source such as a well, reservoir, pond, stream, or where anti-
freeze or other chemicals are added, or having combined industrial and fire systems with
or without storage tanks or pumper connections, shall be equipped with a Reduced
Pressure Zone (RPZ) backflow prevention assembly or an Air Gap (AG).
The fire service systems, including the backflow prevention device, shall be
designed to provide the flow volume and pressure required to properly operate the last
sprinkler head in the system, furthest from the backflow device. Where pressure drop
through a single backflow prevention device does not provide adequate flow and
pressure, multiple backflow prevention devices may be installed in parallel when
approved by the Fire Marshal.
Certified plans for fire service systems and connections, including backflow prevention
devices, shall be submitted to the City in duplicate, as a minimum, prior to construction
and/or installation. Revisions to the plans, based on comments from the City, if any, shall
be re-submitted for additional review. Construction and/or installation shall not proceed
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until the final or revised plans are approved by the City. An additional copy of all plans
(initial, revised, and final) should also be submitted to be forwarded to the VDH for review
and comment.
13-260 SYSTEM AND DEVICE REQUIREMENTS
13-260.1 IDENTIFICATION OF POTABLE AND NON-POTABLE WATER
Potable and non-potable water pipes shall be identified and marked as follows:
A. Where two (2) or more piping systems are installed, each system shall be
identified by color markings or metal tags in accordance with the applicable
plumbing code.
B. Where piping systems are insulated, the identification markings shall be
placed on the exterior of the insulation.
C. Piping on the outlet side (downstream) of backflow preventers shall be
identified as "Non-Potable Water”; and
D. Markings on piping systems shall be placed every five (5) feet.
13-260.2 APPROVED BACKFLOW PREVENTION DEVICES
Backflow prevention devices installed within the boundaries of the City of
Manassas shall be those listed in the most current Seal Authorizations booklet
published quarterly by the ASSE. All approved devices must display the ASSE
certification number and seal on the exterior surface of the body of the device. All
approved devices shall be installed in the orientation (horizontal or vertical) and
configuration (“N”, “S”, or “U” shape) indicated in the listing, and be equipped with
the valves specified in the listing or this standard. A copy of the current ASSE
Seal Authorizations booklet is maintained by the Water and Sewer Division and
the Inspections/Fire Marshal’s Office. Additionally, you may call the ASSE at (440)
835-3040 or visit their web site at www.asse-plumbing.org.
13-22
Typically, backflow prevention devices approved by the ASSE are also
approved by the FCCCHR/USC. If a specific device is not indicated on the most
current ASSE listing, the consumer or his designated representative may request
to install a device identified on the most current FCCCHR/USC approval listing.
However, the City, on a case-by-case basis, shall first review and approve the
device. If approved, the device must be installed in the orientation, configuration,
and with the valves specified in the listing or standard, or as directed by the City.
13-260.3 PROHIBITED INTERCONNECTIONS AND DEVICES
The following interconnections and devices are prohibited:
A. Interconnections between the City’s waterworks and another public
waterworks or water supply, unless approved by the City and/or the VDH;
B. Interconnections between a private water supply and the City’s waterworks;
C. Interchangeable connections or changeover devices, unless approved by
the City. These types of interconnections and devices have limitations,
shall only be used on a temporary basis, and must be continuously
monitored while installed; and
D. Backflow prevention devices that are not ASSE or FCCCHR/USC
approved.
13-260.4 BACKFLOW PREVENTION DEVICE INSTALLATION
General Requirements:
A. Backflow prevention devices shall be installed at a location and in a manner
approved by the City and as outlined in this standard. Existing backflow
prevention devices approved by the City and the VDH prior to the effective
date of the applicable regulations, shall, except for maintenance
requirements, be excluded from the requirements of Section 13-260 of this
Standard, as long as the City and the VDH are assured that the device(s)
will provide adequate protection to the waterworks and the consumer's
13-23
water system from potential contamination and/or pollution in the event
backflow were to occur;
B. Backflow prevention devices shall be protected from freezing, flooding, and
mechanical and structural damage;
C. Backflow prevention devices shall not be installed in pits, sumps, vaults, or
other below grade locations; and
D. Backflow prevention devices shall be readily accessible for inspection and
maintenance.
Specific Requirements:
A. When installed on the interior of a building, the area in which the backflow
prevention device is installed must be capable of maintaining a minimum
temperature of fifty (50) degrees Fahrenheit (ºF), except those devices
approved for, removed, and reinstalled seasonally.
B. When installed on the exterior of a building, the backflow prevention device
must be located inside of an ASSE Standard 1060 approved heated
enclosure, unless the device is approved by the City for seasonal use as
described in “A” above. Additionally, a means of protecting the backflow
prevention device and/or the enclosure from structural damage may be
required if the location is exposed to vehicular traffic, at the discretion of the
City;
C. Backflow prevention device enclosures shall be secured to a base frame
and platform, and locked to prevent vandalism and theft;
D. Backflow prevention devices shall be installed upstream of any pressure
regulating or reducing valve or device;
E. Testable types of backflow prevention devices shall be provided with the
petcock fittings at approved locations for connecting test instrument hoses.
Gauges, valves, other equipment items or water connections shall not be
installed in or to the petcocks, other than those used portability for testing
purposes;
13-24
F. Vacuum breaker backflow prevention devices shall only be used in areas
where water spillage is not objectionable. Alternatively, ASSE approved
spill-resistant vacuum breakers (SVB) may be used in these situations;
G. AVB backflow prevention devices shall be installed in a vertical orientation
only, downstream of the last valve in a system, and at a minimum of six (6)
inches above the downstream piping, fixture, flood level rim, outlet, or
highest point of water use. The AVB shall not be used where it will operate
under continuous supply pressure for more than twelve (12) hours in a
twenty-four (24) hour period. An AVB shall not be installed inside of a fume
hood;
H. PVB backflow prevention devices shall be installed in a vertical position and
at a minimum of twelve (12) inches above the downstream piping, fixture,
flood level rim, outlet, or highest point of water use. The PVB may be used
where it will operate under continuous pressure for more than twelve (12)
hours at a time. A PVB shall not be installed inside of a fume hood;
I. RPZ and DCV assembly backflow prevention devices located on the interior
of a building shall be installed at a minimum of eighteen (18) inches and a
maximum of forty-eight (48) inches above the finished floor elevation. RPZ
and DCV devices located on the exterior of a building shall be installed at a
minimum of eighteen (18) inches and a maximum of twenty-four (24) inches
above the grade elevation. Minimum and maximum height clearances are
to be measured from the floor or grade elevation to the centerline of the
backflow prevention device;
J. A minimum of six (6) feet of headroom shall be provided in the area in
which the RPZ or DCV is installed, and a minimum of thirty (30) inches of
unobstructed space shall be provided in front of each device, in order to
provide adequate access for maintenance;
K. A minimum of eighteen (18) inches of clearance shall be provided behind
RPZ and DCV backflow prevention devices larger than two (2) inches. A
minimum of twelve (12) inches of clearance shall be provided behind RPZ
and DCV devices two (2) inches and smaller;
13-25
L. RPZ and DCV backflow prevention devices shall be installed in a horizontal
orientation unless ASSE approved for other specified orientations, or if
otherwise approved by the City;
M. An approved AG shall be maintained between the pressure differential relief
valve outlet of an RPZ device and a drain inlet, if any. An AG device
manufactured specifically for the RPZ is the preferred method for attaching
a drain pipe to convey water discharges, if any, away from the device and
its location. A drain pipe from an RPZ shall be sized to handle the
maximum discharge output of the device’s pressure differential relief valve;
N. RPZ and DCV backflow prevention devices shall be installed with a Y-type
strainer directly upstream of the device, except in fire sprinkler systems
which must be approved by the City. Strainers are recommended for other
types of backflow prevention devices to prevent premature failure of the
device from debris that may enter the waterworks;
O. RPZ and DCV backflow prevention devices must be sized hydraulically,
accounting for volume and pressure requirements of the water service and
head loss through the device;
P. All backflow prevention devices with relief mechanisms or vents shall have
the relief or vent outlet piped to a floor drain, floor sink, or other approved
receptor and sized to handle the peak discharge from the device;
Q. Certified plans for the installation of backflow prevention devices in new
construction, or when extensive modifications are planned for existing
facilities, shall be submitted to the City in duplicate prior to construction or
installation, for review, comment, and approval. Revised plans, if required,
shall be re-submitted to the City for further review and comment.
Construction and installation may proceed only after final approval by the
City; and
R. Testable types of backflow devices shall be installed in an area exclusively
reserved for such devices. Related apparatus, including valves, water
meters, and fire sprinkler standpipes or manifolds, shall be permitted to
share the same area, provided the specified dimensional requirements can
be maintained.
13-26
S. An ASSE 1022 or ASSE 1032 backflow prevention device shall be installed
in the primary potable water supply to all carbonated beverage systems. In
addition to the primary backflow prevention device, a secondary ASSE
1022 or ASSE 1032 backflow prevention device shall be installed in the
water supply between the carbonation system pump and the carbonation
tank. Other (additional) backflow prevention devices may also be required
in water supply pipes, lines, or tubing used to complete the installation of a
carbonation system, at the discretion of the City.
T. There shall be no copper pipe, tubing, fittings, or connectors located
downstream of the primary backflow prevention device installed in a
carbonated beverage system.
Also see Table 1, Summary of Backflow Prevention Device
Requirements. Additionally, information may be provided in the applicable
plumbing code; the ASSE, FCCCHR/USC and AWWA Standards and technical
guidelines, and the manufacturer’s installation instructions.
13-260.5 SHUT-OFF VALVE REQUIREMENTS
Valves are required on backflow prevention devices, as follows:
A. Resilient wedge gate valves, butterfly valves, or ball valves shall be
required on the inlet and outlet of RPZ, DCV, and on the inlet of AVB
devices.
B. Full port valves shall be required on devices two (2) inches and
smaller; and
C. Valves shall be affixed directly to the body of RPZ, DCV, and PVB
backflow prevention devices and are considered an integral part of an
approved device.
RPZ, DCV, PVB, and AVB devices without the required valves at the
specified locations are not ASSE approved and shall not be installed.
13-27
13-260.6 IRRIGATION SYSTEMS
An approved backflow prevention device shall be installed on the water
service line or supply pipe to each lawn sprinkler or other irrigation system, as
follows:
A. An AG, RPZ, or PVB backflow prevention device shall be installed in
the water supply pipe to a lawn sprinkler or other irrigation system equipped
with surface or below grade sprinkler heads in a consumer’s water system;
and
B. If the sprinkler or irrigation system is also connected to an auxiliary
water source, then adequate backflow protection shall be provided, as
determined and approved by the City or VDH; and
Certified plans for the installation of backflow prevention devices in lawn
sprinkler or irrigation systems shall be submitted to the City in duplicate for review,
comments, and approval prior to installation or construction. Revised plans, if
required, shall be re-submitted to the City for further review and comments.
Construction of the irrigation system and installation of the backflow prevention
device shall not proceed without final approval of the City.
13-260.7 BYPASS ARRANGEMENTS
Bypasses are typically installed in water supply pipes to various type of
systems and equipment, especially around pressure reducing valves, pressure
relief valves, large water meters, etc. This is done in order to provide a continuing
water supply during routine or emergency maintenance of the item. However,
bypasses around A backflow prevention device defeats its purpose and renders it
ineffective. Therefore, bypass arrangements shall only be allowed around
backflow prevention devices when an equivalent type of backflow prevention
device is also installed in the bypass pipe.
13-28
13-260.8 REDUNDANT BACKFLOW PREVENTION DEVICES
Where necessary to maintain the required water supply pressures and flow
volumes to facilities such as hospitals, clinics, medical examination and outpatient
facilities, morgues, laboratories, dental facilities, nursing homes, and industrial
facilities, redundant (repetitive) backflow prevention devices shall be installed in
parallel and sized for peak water demand to ensure a continuous and
uninterrupted flow of water to the facility.
13-260.9 AIR GAP CRITERIA
Air Gaps not previously discussed and specified in Article 13 or the
applicable codes or standards, shall be installed and maintained according to the
following:
A. ASSE Standard 1006, Residential Use Dishwashers; and
B. ASSE Standard 1007, Home Laundry Equipment.
The minimum required air gap shall be as follows:
A. Two (2) times the diameter of the outlet;
B. Measured vertically from the lowest end of the outlet to the flood level rim of
the fixture or receptor into which it discharges; and
C. NEVER less than one (1) inch.
AG criteria can also be found in Table 13-1, Summary of Backflow Prevention
Device Requirements, provided at the end of this Article.
13-260.10 HEAT TRANSFER SYSTEMS
Backflow prevention device requirements for heat transfer systems shall be
as follows:
13-29
A. No backflow prevention device shall be required on heat transfer systems
using potable water as the transfer fluid in a closed loop arrangement free
from exposure to external fluids and of single wall construction on drain-
down solar water heaters, integrated collector storage (ICS) solar heaters,
and water-to-air (heat only) coils;
B. Heat exchangers utilizing a toxic transfer fluid shall be separated from the
potable water by double-wall construction. An AG open to the atmosphere
shall be provided between the two walls;
C. Heat exchangers utilizing a non-toxic transfer fluid are allowed to be of
single-wall construction. However, an AG or RPZ backflow prevention
device shall be required on the water supply pipe;
D. Water used for heat transfer or for cooling of equipment or processes shall
not be returned to the consumer’s water system or the waterworks; and
E. Heat exchangers must be approved by the City prior to installation.
13-260.11 BOTTOM FEED HOT WATER TANKS
Bottom feed hot water tanks shall have a vacuum relief valve installed in the
water supply pipe to prevent back-siphonage. The vacuum relief valve shall
conform to the American National Standards Institute (ANSI) Standard Z21.22.
13-270 MAINTENANCE OF BACKFLOW PREVENTION DEVICES
All backflow prevention devices shall be maintained in good operating condition at
all times, in accordance with the requirements specified below and the applicable
regulations, ordinances, and codes. All maintenance costs shall be the responsibility of
the consumer, tenant, manager, operator, or property owner.
13-270.1 INSPECTION
Backflow prevention devices, including air gaps, shall be inspected after
initial installation and subsequent repair or replacement, and annually to
determine:
13-30
A. The device provides adequate backflow protection against the degree of
hazard presented by the downstream equipment, piping, plumbing fixture,
or non-potable system or equipment;
B. The device is installed in accordance with the minimum requirements of this
standard;
C. The device is not bypassed, and if a bypass is installed it is equipped with
equal backflow protection;
D. The device is not leaking, weeping, or damaged;
E. The device is not equipped with unapproved appurtenances; and
F. The device is maintained, including operational tests and overhaul and
replacement at the specified intervals, in accordance with the requirements
of the applicable regulations, ordinances, and codes.
G. Air gaps are not circumvented. Backflow prevention devices shall be inspected annually at the consumer,
tenant, operator, manager, or property owner’s expense. Inspections shall be
performed by the City for each new or replacement backflow prevention device, or
for existing backflow prevention devices in accordance with the frequency
specified in applicable regulations and ordinances, or more frequently at the
discretion of the City.
The City shall install a consecutively numbered identification and inspection
tag to all testable types of backflow prevention devices. The tag shall remain
attached to the device to which it is assigned and shall not be removed without the
written consent of the City. When an existing device is replaced, the City shall be
notified and a new tag shall be installed.
Also see Table 13-2, Summary of Backflow Prevention Device
Requirements.
13-31
13-270.2 TESTING
All testable types of backflow prevention devices, i.e., the RPZ, DCV, and
PVB assemblies, shall be tested as follows:
A. Upon initial installation;
B. Upon replacement of an existing device:
C. Upon repair, and
D. Annually, as a minimum.
More frequent tests may be required under certain circumstances or
conditions, at the discretion of the City.
A test failure indicates a malfunction of the device and could be a sign of
failure of an internal component. Devices that fail a test shall immediately be
cleaned, repaired or replaced, as necessary, and re-tested, to ensure continued
proper operation and backflow protection.
13-270.2.1 TEST PROCEDURES
The procedures for testing backflow prevention devices shall be in
accordance with the most current editions of the following:
A. Manual of Water Supply Practices M-14, Recommended Practice for
Cross-Connection Control and Backflow Prevention, AWWA;
B. Manual of Cross-Connection Control, FCCCHR/USC; or
C. The manufacturer’s instructions.
The AWWA and FCCCHR/USC procedures are recommended since they
include additional steps for testing and troubleshooting a backflow
prevention device that are not normally included in the manufacturer’s
instructions.
13-32
13-270.2.2 TEST RECORDS
The results of all tests conducted on backflow prevention devices
shall be recorded on a Backflow Prevention Device Test Report form
provided by the City. Blank copies of the form can be obtained from the
Water and Sewer Division or the Inspections/Fire Marshal’s Office. The
test reports shall be maintained as follows:
A. One (1) copy to the tester;
B. One (1) copy to the consumer (tenant, manager, operator, or
property owner),
C. One (1) copy, as a minimum, to the City; and
D. For a period of 10 years (as required by applicable regulations).
Also see Table 13-1, Summary of Backflow Prevention Device
Requirements.
13-270.2.3 TESTER CERTIFICATION
Backflow prevention device testers shall hold a certificate of
completion from a Virginia Board for Contractors Approved Backflow
Prevention Device Worker School. Certification by these schools only
permits testing of backflow prevention devices. Maintenance, repair and
replacement of backflow prevention devices shall be performed by a
tradesman with a valid certificate to perform these tasks.
13-270.3 MAINTENANCE
In addition to the testing requirements specified in sub-section 13-
270.2, backflow prevention devices shall be maintained as follows:
13-33
A. RPZ, DCV, and PVB backflow prevention devices shall be
overhauled (replacement of internal rubber components, as a minimum)
every five (5) years. NOTE: REPLACEMENT, AS A SUBSTITUTE FOR
OVERHAUL, IS OPTIONAL; and
B. DC/IAV and DC backflow prevention devices shall be replaced every
five (5) years, or more frequently if an inspection of the device by the City
indicates leakage, damage, corrosion, or other probable causes of failure;
and
C. Receipts for the installation, repair, replacement, and testing of
backflow prevention devices shall be maintained by the consumer, tenant,
manager, operator, or property owner as evidence that the required
maintenance is performed.
Also see Table 13-1, Summary of Backflow Prevention Device
Requirements.
13-34
Table 13-1, Summary of Backflow Prevention Device Requirements
The following table summarizes the requirements, applications, and uses of backflow prevention devices. It is not intended to and may not provide all requirements for each backflow prevention device. See the referenced sections, the applicable regulations, codes and technical guidelines, and the backflow prevention device manufacturer’s literature for more information.
Device Type
(Acronym)
Applicable
Standard & No.
Pressure
Application(s)
Pressure
Condition(s)
Degree of Hazard
Application
Installation
Clearances &
Orientation
Section Reference
Typical Use
Application(s) &
Comments
Air Gap
(AG)
ANSI A112.2.1
Back-siphonage Back Pressure
Continuous
High
2x diameter of outlet opening; never less than 1.”
13-100; 13-240.1; 13-260.2; 13-260.3: 13-260.4; 13-260.5; 13-260.6; 13-260.9; 13-260.10; and 13-270
Sinks, bathtubs, process make-up tanks, residential dishwashers (ASSE 2006) & clothes washers (ASSE 1007)
Atmospheric
Vacuum Breaker (AVB)
ASSE 1001
Backsiphonage
Intermittent (not
more than 12 hours at a time)
High/Low
Vertical only; no downstream valves; minimum of 6” above highest downstream piping, fixture, flood level rim, outlet, or highest point of water use; not for inside of fume hoods.
13-100; 13-240.2; 13-260.3; 13-260.4; 13-260-5; 13-260.7; 13-260.11; and 13-270
Low flow items such as lab sinks, soap dispensers & appliances not subject to back pressure; do not install where water spillage is objectionable; spill-resistant type allowed.
Hose Connection Vacuum Breaker
(HCVB)
ASSE 1011
Back-siphonage
Intermittent
Low
Device must be locked-in-place.
13-100; 13-240.5; 13-260.2; 13-260.3; 13-260.4; 13-260.5; and 13-270
Hose bibs; sillcocks; wall hydrants; freeze-proof type required for exterior installations; not for use where there is more than 10’ of head.
Dual Check with
Intermediate Atmospheric Vent
ASSE 1012
Back-siphonage
Continuous
Low
Horizontal or vertical; air gap required on vent outlet drain.
13-100; 13-240.5; 13-260.2; 13-260.3; 13-260.4; 13-260.5; and 13-270
Residential boilers; hot tubs; lab equip.; commercial dishwashers; ice machines; carbonated beverage systems; replace every 5 yrs.
13-35
Table 13-1, Summary of Backflow Prevention Device Requirements (continued)
Device Type
(Acronym)
Applicable
Standard & No.
Pressure
Application(s)
Pressure
Condition(s)
Degree of Hazard
Application
Installation
Clearances &
Orientation
Section Reference
Typical Use
Application(s) &
Comments
Reduced Pressure
Zone Assembly (RPZ)
ASSE 1013
Back-siphonage Back Pressure
Continuous
High
Horizontal unless ASSE approved for vertical; minimum of 24” above finished floor for interior devices, 18” above grade for exterior devices; maximum of 48” above finished floor for interior devices, 24” above grade for exterior devices; no pit installations.
513-100; 13-240.1; 13-240.4; 13-260.2; 13-260.3; 13-260.4; 13-260.5; 13-250; 13-260.6; 13-260.7; 13-260.8; 13-260.9; 13-260.10; and 13-270
Facilities per 13-220; chemical tanks; cooling towers; chilled water systems; commercial boilers; swimming pools; certain hospital equipment; solar heating systems; lawn sprinklers; overhaul or replace every 5 years; test annually.
Double Check
Valve Assembly (DCV)
ASSE 1015
Back-siphonage Back Pressure
Continuous
Low
Horizontal unless ASSE approved for vertical; minimum of 24” above finished floor for interior devices, 18” above grade for exterior devices; maximum of 48” above finished floor for interior devices, 24” above grade for exterior devices; no pit installations.
13-100; 13-240.3; 13-250; 13-260.2; 13-260.3; 13-260.4; 13-260.5; 13-260.7; 13-260.8; and 13-270
Washdown racks or equipment; large food processing equipment; fire sprinkler systems; lawn sprinklers; overhaul or replace every 5 years; test annually.
Pressure Vacuum
Breaker (PVB)
ASSE 1020
Back-siphonage
Continuous (more
than 12 hours)
High
Vertical only; minimum of 12” above highest downstream piping, fixture, flood level rim, outlet, or highest point of water use; not for inside of fume hoods.
13-100; 13-240.2; 13-260.2; 13-260.3; 13-260.4; and 13-270
Degreasing equip.; lab equip.; photo developing tanks; lawn sprinklers; do not install where water spillage is objectionable; overhaul every 5 years; test annually.
13-36
Table 13-1, Summary of Backflow Prevention Device Requirements (continued)
Device Type
(Acronym)
Applicable
Standard &
No.
Pressure
Application(s)
Pressure
Condition(s)
Degree of
Hazard
Application
Installation
Clearances
&
Orientation
Section Reference
Typical Use
Application(s) &
Comments
Dual Check
Valve (DC)
ASSE 1024
Back-
siphonage Backpressure
Intermittent Continuous
No or low flow
Low/Moderate
Vertical or horizontal
13-100; 13-240.5; 13-260.2; 13-260.3; 13-260.4; and 13-270
Residential water service lines; residential fire sprinkler service lines; sink spray hoses; tea/coffee equipment; carbonated beverage systems (secondary protection only); replace every 5 years
Lab Faucet Backflow Device (LFBD)
ASSE 1035
Back-
siphonage Back Pressure
Intermittent
Low or no flow
Low
Vertical
13-100; 13-240.5; 13-260.2; 13-260.3; 13-260.4; and 13-270
Lab sink faucet outlets; other sink applications.
Backflow
Preventer for Carbonated Beverage Systems
ASSE 1022 ASSE 1032
Back-
siphonage Back Pressure
Continuous Intermittent
Low Moderate
Vertical or horizontal; primary & secondary devices required; no copper pipe downstream of primary device.
13-100; 13-240.5; 13-260.2; 13-260.3; 13-260.4; and 13-270
Carbonated beverage systems (primary and/or secondary)
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