Water Conditioning GlossaryBase - A substance which releases hydroxyl ions whendissolved in water. Bases react with acids to form aneutral salt and water.

Bed - The ion exchange or filter media in a column orother tank or operational vessel.

Bed Depth - The height of the ion exchange or filter mediain the vessel after preparation for service.

Boiling Point - The temperature at which a substance willchange from a liquid state to a gaseous or vapor state.

Brackish Water - Water containing between 1000 and1500 mg/l of dissolved solids is generally considered tobe brackish.

Brine (R.O.) - Same as reject water. One of two streamsof fluids generated by a reverse osmosis unit. It containsthe impurities removed from the feed water.

Brine (Softening) - A strong solution of salt(s), such assodium chloride, and water used in the regeneration ofion exchange water softeners but also applied to themixed sodium, calcium and magnesium chloride wastesolution from regeneration.

Calcium (Ca) - One of the principal elements makingup the earth’s crust, the compounds of which, whendissolved, make the water hard. The presence of calciumin water is a factor contributing to the formation of scaleand insoluble soap curds which are a means of clearlyidentifying hard water.

Calcium Hypochlorite (CaCl2O2) - A chemical compoundused as a bleach and a source of chlorine water treatment;specifically useful because it is stable as a dry powderand can be formed into tablets.

Capacity - An expression of the quantity of an undesirablematerial which can be removed by a water conditionerbetween servicing of the media (i.e. cleaning, regenerationor replacement) as determined under standard testconditions. For ion exchange water softeners, the capacityis expressed in grains of hardness removal betweensuccessive regenerations and is related to the pounds ofsalt used in regeneration. For filters, the capacity may beexpressed in the length of time or total gallons deliveredbetween servicing.

Caustic Soda - The common name for sodium hydroxide.

Cation - An ion with a positive electrical charge, such ascalcium, magnesium and sodium.

Cation Exchange - Ion exchange process in which cationsin solution are exchanged for other cations from an ionexchanger.

Cellulose Acetate (CA) and Cellulose Triacetate (CTA) - Afamily of synthetic materials based on cellulose usedto make reverse osmosis membranes. While CTA issuperior to CA, under adverse water conditions both areeffective in removing a wide spectrum of impurities fromwater. The disadvantage of cellulose-type membranesis that they are subject to bacterial attack, particularly inunchlorinated water supplies. CTA has superior bacterialresistance.

Absorption - The process in which one substance istaken into the body of another substance, termed theabsorbent. An example is the absorption of water intosoil.

Acid - A substance which releases hydrogen ions whendissolved in water. Most acids will dissolve the commonmetals and will react with a base to form a neutral saltand water.

Activated Carbon - A granular material usually producedby the roasting of cellulose base substances, such aswood or coconut shells, in the absence of air. It has a veryporous structure and is used in water conditioning as anadsorbent of organic matter and certain dissolved gases.Sometimes called “activated charcoal.”

Adsorption - The process in which matter adheres to thesurface of the adsorbent.

Aeration - The process in which air is brought into intimatecontact with water, often by spraying water through air orby bubbling air through water. Aeration may be used toadd oxygen to the water for oxidation of matter such asiron or to cause the release of dissolved gases such ascarbon dioxide or hydrogen sulfide from the water.

Alkalinity - The quantitative capacity of a water or watersolution to neutralize an acid. It is usually measured bytitration with a standard acid solution of sulfuric acid andexpressed in terms of its calcium carbonate equivalent.

Anion - A negatively charged ion in solution such asbicarbonate, chloride or sulfate.

Anion Exchange - An ion exchange process in whichanions in solution are exchanged for other anions froman ion exchanger. In demineralization, for example,bicarbonate, chloride and sulfate anions are removedfrom solution in exchange for a chemically equivalentnumber of hydroxide anions from the anion exchangeresin.

Aquifer - A layer or zone below the surface of the earthwhich is capable of yielding a significant volume of water.Atom - The smallest particle of an element that can existeither alone or in combination with smaller particles ofthe same element or of a different element.

Attrition - The process in which solids are worn down orground down by friction, often between particles of thesame material. Filter media and ion exchange materialsare subject to attrition during backwashing, regenerationand service.

Backwash - The process in which beds of filter or ionexchange media are subjected to flow opposite to serviceflow direction to loosen the bed and to flush suspendedmatter collected during the service run to waste.Bacteria - Unicellular micro-organisms which typicallyreproduce by cell division. Although usually classed asplants, bacteria contain no chlorophyll.

Bacteriostatic - A feature of a carbon filter that issupposed to inhibit the growth of bacteria within the filter- usually by the addition of silver.

108 Accessories

Water Conditioning Glossaryions are removed by an ion exchange resin for achemically equivalent amount of hydrogen ions. Thehydrogen and hydroxide ions introduced in this processunite to form water molecules. The term is often usedinterchangeably with demineralization.

Disinfection - A process in which pathogenic, diseaseproducing bacteria are killed. May involve disinfectingagents such as chlorine or physical processes such asheating.

Dissolved Solids - The weight of matter in true solutionin a stated volume of water. Includes both inorganic andorganic matter and is usually determined by weighing theresidue after evaporation of the water at 105°F or 180°C.

Distillation - The process in which a liquid, such as water,is converted into its vapor state by heating and the vaporcooled and condensed to the liquid state and collected.Used to remove solids and other impurities from water.Multiple distillations are required for extreme purity.DNA - Deoxyribonucleic acid constituting the geneticmaterial of the chromosome in a cell, responsible forreproductive characteristics.

Drawdown - The amount of water delivered by thestorage tank between pump shut-down and pump start.

E Coli (Escherichia Coli) - One of the members of thecoliform group of bacteria indicating fecal contamination.

Effluent - The stream emerging from a unit, systemor process such as the softened water from an ionexchange softener.

Exhaustion - The state of an ion exchange material inwhich it is no longer capable of effective function due tothe depletion of the initial supply of exchangeable ions.The exhaustion point may be defined in terms of a limitingconcentration of matter in the effluent or, in the case ofdemineralization, in terms of electrical conductivity.

Fecal - Matter containing or derived from animal orhuman waste.

Feed Pressure - The pressure at which water is suppliedto the R.O. module.

Feed Water - A term which refers to the water supplythat is put into a water treatment system for processing(removal of impurities.)

Flocculation - The agglomeration of finely dividedsuspended solids into larger, usually gelatinous, particles.The development of a ‘floc’ after treatment with acoagulant by gentle stirring or mixing.

Flow Control - A device designed to limit the flow ofwater or regenerant to a predetermined value over abroad range of inlet water pressures.

Flow Rate - The quantity of water or regenerant whichpasses a given point in a specified unit of time, oftenexpressed in gallons per minute.

Flux - The flow rate of water through reverse osmosismembranes, per square foot of surface.

Fouling - The process in which undesirable foreign matteraccumulates in a bed of filter media or ion exchanger,

Channeling - The flow of water or other solution in alimited number of passages in a filter or ion exchangebed instead of distributed flow through all passages inthe bed.

Chloramines - Chemical complexes formed from thereaction between ammonia and chlorine. They are presentlybeing used to disinfect municipal water supplies because,unlike chlorine, they do not combine with organics in thewater to form potentially dangerous carcinogens such astrihalomethanes (THMs). Chloramines can exist in threeforms, the proportions of which depend on the physicaland chemical properties of the water. Water containingchloramines may not be used for fish or kidney dialysisequipment.

Chlorides (Cl) - an ion which forms acids when combinedwith hydrogen and salts when combined with metal ions.Chlorides can be corrosive and impart a salty taste towater.

Chlorine (Cl2) - A gas widely used in the disinfection ofwater and an oxidizing agent for organic matter, iron, etc.

Coagulant - A material, such as alum, which willform a gelatinous precipitate in water and cause theagglomeration of finely divided particles into largerparticles which can then be removed by settling and/orfiltration.

Colloid - Very finely divided solid particles which will notsettle out of a solution; intermediate between a truedissolved particle and a suspended solid which will settleout of solution. The removal of colloidal particles usuallyrequires coagulation to form larger particles which maybe removed by sedimentation and/or filtration.

Compensated Hardness - A calculated value based onthe total hardness - the magnesium to calcium ratio andthe sodium concentration of a water. It is used to correctfor the reductions in hardness removal capacity causedby these factors in cation exchange water softeners. Nosingle method of calculation has been widely accepted.

Conductivity - The quality or power to carry electricalcurrent. In water, the conductivity is related to theconcentration of ions capable of carrying electrical current.

Contact Time - The length of time water is in direct contactwith activated carbon (R.O.) or chlorine (chlorinationsystem.) This is a major factor in determining howeffectively impurities will be removed.

Corrosion - The destructive disintegration of a metal byelectrochemical means.

Cycle Time - The amount of time in seconds elapsedbetween pump start and pump shut-down.

Dechlorination - The removal of excess chlorine residual,often after super-chlorination.

Deionization (DI) - The removal of all ionized mineralsand salts (both organic and inorganic) from a solution bya two-phase ion exchange procedure. First, positivelycharged ions are exchanged for a chemically equivalentamount of hydrogen ions. Second, negatively charged

109Glossary

Water Conditioning Glossaryexchange for other ions in a surrounding solution; thedirection of the exchange depends upon the affinitiesof the ion exchanger for the ions present and theconcentrations of the ions in the solution.

Iron (Fe) - An element often found dissolved in groundwater (in the form of ferrous iron) in concentrationsusually ranging from 0-10 ppm (mg/l). It is objectionablein water supplies because of the staining caused afteroxidation and precipitation (as ferric hydroxide); becauseof the tastes; and because of unsightly colors producedwhen iron reacts with tannins in beverages such ascoffee and tea.

Iron Bacteria - Organisms which are capable of utilizingferrous iron, either from the water or from steel pipein their metabolism and precipitating ferric hydroxide intheir sheaths and gelatinous deposits. These organismstend to collect in pipelines and tanks during periods oflow flow and to break loose in slugs of turbid water tocreate staining, taste and odor problems.

Magnesium (Mg) - One of the elements making upthe earth’s crust, the compounds of which, whendissolved in water, make the water hard. The presenceof magnesium in water is a factor contributing to theformation of scale and insoluble soap curds.

Manganese (Mn) - An element sometimes founddissolved in ground water, usually with dissolved iron butin lower concentrations. Causes black stains and otherproblems similar to iron.

Manganese Greensand - Greensand which has beenprocessed to incorporate in its pores and on its surfacethe higher oxides of manganese. The product has a mildoxidizing power and is often used in the oxidation andprecipitation of iron, manganese and/or hydrogen sulfideand their removal from water.

Mechanical Filtration - The process of removingsuspended particles from water by a straining action. Thefinest mechanical filters can remove bacteria as small as0.2 microns.

Media - The selected materials in a filter that form thebarrier to the passage of certain suspended solids ordissolved minerals. (Singular of media is medium).

Milligrams per Liter (mg/l) - A unit concentration of matterused in reporting the results of water and wastewateranalysis. In dilute water solutions, it is practically equal toparts per million but varies from the ppm in concentratedsolutions such as brine. As most analysis are performedon measured volumes of water, the mg/l is a moreaccurate expression of the concentration and is thepreferred unit of measure.

Micron - A linear measure equal to one millionth of ameter or .00003937 inch. The symbol for the micron isthe Greek letter “μ”.

Micron Rating - The term applied to a filter or filter mediumto indicate the particle size above which all suspendedsolids will be removed throughout the rated capacity.As used in industry standards, this is an “absolute”not “nominal” rating. (Refer to S-200, Recommended

clogging pores and coating surfaces and thus inhibitingor retarding the proper operation of the bed.

Freeboard - The vertical distance between a bed offilter media or ion exchange material and the overflowor collector for backwash water. The height abovethe bed of granular media available for bed expansionduring backwashing. May be expressed either as a lineardistance or a percentage of bed depth.

Grain (gr) - A unit of weight equal to 1/7000 of a poundor 0.0648 gram.

Grain per Gallon (gpg) - A common basis for reportingwater analysis in the United States and Canada. Onegrain per U.S. gallon equals 17.12 milligrams per liter(mg/l) or parts per million (ppm). One grain per British(Imperial) gallon equals 14.3 mg/l or ppm.

Greensand - A natural mineral, primarily composed ofcomplex silicates, which can be coated with manganeseoxide to form a catalytic absorptive surface. This surfaceis used to attract ferrous iron and manganese as well asto absorb dissolved oxygen which is used to oxidize iron,manganese or hydrogen sulfide.

Hardness - A characteristic of natural water due to thepresence of dissolved calcium and magnesium. Waterhardness is responsible for most scale formation in pipesand water heaters and forms insoluble “curd” when itreacts with soaps. Hardness is usually expressed in grainsper gallon (gpg), parts per million (ppm) or milligrams perliter (mg/l), all as calcium carbonate equivalent.

Hard Water - Water with a total hardness of 1 gpg ormore as calcium carbonate equivalent.

Hydrologic Cycle - The natural water cycle, includingprecipitation of water from the atmosphere as rainor snow, flow of water over or through the earthand evaporation or transpiration to water vapor in theatmosphere.

Hydrogen Sulfide (H2S) - A gas characterized by anoffensive odor, commonly referred to as “rotten egg”odor. Flammable and poisonous in high concentrations,corrosive to most metals and can even tarnish silver.Detectable by most people in concentrations as low as0.5 ppm.

Hydrocharger - Trade name of a particular type of airinduction or injector valve.

Hydrolysis - The chemical degradation of an R.O.membrane in water due to certain conditions such as highpH. Cellulose based membranes are quite susceptible tohydrolysis while the TFC type are virtually immune.

Influent - The stream entering a unit, stream or process,such as the hard water entering an ion exchange watersoftener.

Ion - An atom, or group of atoms, which function as a unitand have a positive or negative electrical charge due tothe gain or loss of one or more electrons.

Ion Exchange - A reversible process in which ionsare released from an insoluble permanent material in

110 Glossary

Water Conditioning GlossaryCommon examples include: oxygen, chlorine, potassiumpermanganate, hydrogen peroxide, iodine and ozone.

Ozone (O3) - An unstable form of oxygen occurring naturallyin the upper atmosphere or artificially produced becauseof its strong oxidizing or disinfection characteristics.

Particle Size - As used in industry standards, the size of aparticle suspended in water as determined by its smallestdimension, usually expressed in microns.

Parts per Million (ppm) - A common basis for reportingthe results of water and waste water analysis, indicatingthe number of parts by weight of water or other solvent.In dilute water solutions, on part per million is practicallyequal to one milligram per liter, which is the preferredunit. 17.12 ppm equals one grain per U.S. gallon.

Pathogen - An organism which may cause disease.

PCB - Polychlorinated Biphenyls - A highly toxic organiccontaminant found in water supplies which is suspectedof causing cancer in humans.

pH - or the potential of hydrogen ion activity orconcentration. pH is a measure of the intensity of theacidity or alkalinity of water on a scale from 0 to 14, with7 being neutral. When acidity is increased, the hydrogenion concentration increases, resulting in a lower pH value.Similarly, when alkalinity is increased, the hydrogen ionconcentration decreases, resulting in higher pH. The pHvalue is an exponential function so that pH is 10 timesas alkaline as pH 9 and 100 times as alkaline as pH 8.Similarly, a pH 4 is 100 times as acid as pH 6 and 1000times as acid as pH 7.

Potassium Chloride (KCl) - a compound consisting ofpotassium and chloride, becoming increasingly popularas a substitute for sodium chloride in regenerating watersofteners.

Potassium Permanganate (KMnO4) - A powerful oxidizingagent consisting of dark purple crystals with blue metallicsheen. Explosive in contact with sulfuric acid or hydrogenperoxide. Increases flammability of combustible materials.Used to renew the black manganese oxide coating ongreensand media.

Precipitate - To cause a dissolved substance to form asolid particle which can be removed by settling or filteringsuch as in the removal of dissolved iron by oxidation,precipitation and filtration. The term is also used to referto the solid formed and the condensation of water in theatmosphere to form rain or snow.

Pre-treatment - Whatever alterations of the raw feedwater are required to prevent damage to the reverseosmosis membrane.

Product Water - The pure water that has been separatedfrom the feed water stream by the reverse osmosismembrane.

Pumping Rate - The amount of actual water that canbe drawn from a pressure system expressed in gallonsper minute (gpm) obtained by dividing the drawdown(gallons) by the cycle time (seconds) and multiplying theresult by 60 (seconds.)

Industry Standards for Household & Commercial WaterFilters.)

Mineral - A term applied to inorganic substances suchas rocks and similar matter found in the earth strataas opposed to organic substances such as plant andanimal matter. Minerals normally have definite chemicalcomposition and crystal structure. The term is alsoapplied to matter derived from minerals such as theinorganic ions found in water. The term has beenincorrectly applied to ion exchangers, even though mostof the modern materials are organic ion exchange resins.

Mineral Salts - The form in which minerals from dissolvedrock exist in water. Same as Total Dissolved Solids. Thisis the so-called inorganic form of minerals. In excess,they cause water to have a disagreeable taste. Some areharmful to human health.

Molecular Weight - The sum of the atomic weights of theindividual atoms (from a periodic chart) that make up amolecule of a particular substance (e.g. H2O) H=1 atomicweight, 0=16 atomic weight, therefore, molecular weight= 2 + 16 = 18.) Cellulose based membranes can removesubstances as light as MW of 300, while TFC typemembranes remove substances as light as MW of 200.

Nanometer - A measure of a wavelength in theelectromagnetic spectrum. One nanometer equals 109meter.

Neutralization - In general, the addition of either anacid or a base to a solution as required to produce aneutral solution. The use of alkaline or basic materials toneutralize the acidity of some waters is common practicein water conditioning.

Organic Iron - A ferrous iron molecule which is envelopedin an organically complex molecule that resists oxidation.May be present in water that contains a great deal ofcolored colloidal turbidity.

Organics - Any of the compounds whose chemicalstructure is based on carbon (e.g. carbon dioxide, wood,sugar, protein, plastics, methane, THM, TCE, etc.)

Osmosis - A process of diffusion of a solvent, suchas water through a semipermeable membrane, whichwill transmit the solvent but impede most dissolvedsubstances. The normal flow of solvent is from the dilutesolution to the concentrated solution. (See ReverseOsmosis).

Osmotic Pressure - The pressure created by the tendencyof water to flow in osmosis. Every 100 ppm of TDSgenerates about 1 pound per square inch (psi) of osmoticpressure. This osmotic pressure must first be overcomeby the water pressure for the reverse osmosis membraneto be effective.

Oxidation - A chemical process in which electrons areremoved from an atom, ion or compound. The additionof oxygen is a specific form of oxidation. Combustion isan extremely rapid form of oxidation while the rusting ofiron is a slow form.

Oxidizing Agents - Any substance that oxidizesanother substance and is itself reduced in the process.

111Glossary

Water Conditioning Glossarysoaps are soluble and useful but can be converted toinsoluble calcium and magnesium soaps (curd) by thepresence of these hardness ions in water.

Soda Ash - The common name for sodium carbonate, achemical compound used as an alkaline builder in somesoap and detergent formulations to neutralize acid waterand in the lime soda ash water conditioning process.

Total Hardness - The sum of all hardness constituentsin a water, expressed as their equivalent concentrationof calcium carbonate. Primarily due to calcium andmagnesium in solution but may include small amountsof metals, such as iron, which can act like calcium andmagnesium in certain reactions (see Hardness.)

Toxic - Having an adverse physiological effect on man.

Toxic Metals - Elemental metals that find their wayinto water supplies from natural and industrial sourcesand which are detrimental to human health (e.g. lead,cadmium, mercury, arsenic.)

Toxic Organics - Carbon-based chemicals which arefrequently found in our water supplies and are harmfulto human health. They are usually from agricultural andindustrial effluents and hazardous waste dumps (e.g.TCE, PCB, DCBP, pesticides, etc.)

Turbidity - Suspended biological, inorganic and organicparticles in water which may be in sufficient amount tomake the water seem cloudy (see Sediment.)

Virus - The smallest form of life known to be capable ofproducing disease of infection, usually considered to beof large molecular size. They multiply by assembly ofcomponent fragments in living cells, rather than by celldivision as do most bacteria.

Volatile Organic Chemical (VOC) - Chemicals orcompounds with boiling points below 212°F, facilitatingtheir evaporation before water.

Water Softening - The removal of calcium and magnesium,the ions which are the principal cause of hardness, fromwater.

Quartz - A high grade of glass made using quartz sand.

Raw Water - Untreated water or any water before itreaches a specific water treatment device or process.

Recovery - The amount of product water as comparedwith the total amount of feed water. This will give ameasure of the efficiency of operation. For example,starting with 10 gallons of feed water, if 6 gallons isproduct water and 4 gallons reject water, the recoveryis 60%.

Regenerant - A solution of a chemical used to restore thecapacity of an ion exchange or oxidation system.

Regeneration - In general, includes the backwash, brineand fresh water rinse steps necessary to prepare a watersoftener exchange bed for service after exhaustion.Specifically, the term may be applied to the “brine” stepin which the sodium chloride solution is passed throughthe exchanger bed. The term may also be used for similaroperations relating to demineralizers and certain filters.

Rejection - The percentage of TDS removed from thefeed water. Typically greater than 90% rejection isachieved with reverse osmosis.

Reject Water (same as Brine) - That portion of the feedwater that does not pass through the R.O. membraneand which carries the remaining impurities to the drain.

Residual Chlorine - Chlorine remaining in a treatedwater after a specified period of contact time to provideprotection throughout a distribution system. Thedifference between the total chlorine added and thatconsumed by oxidizable matter.

Resin - Synthetic organic ion exchange material such asthe high capacity cation exchange resin widely used inwater softeners.

Reverse Osmosis (R.O.) - A process that reverses, by theapplication of pressure, the flow of water in the naturalprocess of osmosis so that the water passes from themore concentrated to the more dilute solution through asemi-permeable membrane.

Sediment - The sum of particles of dirt, clay, silt andvegetation which float or are suspended in water and canbe removed by mechanical filtration. See Turbidity.

Semi-permeable - A term which applies to specialmaterials, both natural and synthetic, which allowcertain substances such as water to pass through (topermeate) while blocking or rejecting the passage ofother substances such as dissolved solids and organics.

Service (Peak) Flow Rate - The greatest amount of water(expressed in gallons per minute) that a particular filtercan effectively process based on short pump runs of lessthan 10 to 15 minutes maximum.

Sequester - A chemical reaction in which certain ionsare bound into a stable, water soluble compound, thuspreventing undesirable action by the ions.

Soap - One of a class of chemical compounds whichpossesses cleaning properties, formed by the reaction ofa fatty acid with a base of alkali. Sodium and potassium

112 Glossary