There are some common terms used in the discussion of Water Treatment that you need to know:

Absolute Filter Rating

Filter rating meaning that 99.9 % (or essentially all) of the particles larger than a specified micron rating will be trapped on or within the filter.

Absorption

The process in which one substance penetrates into the body of another substance, termed the absorbent. An example is the absorption of water into soil.

Action Level

The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow. The action level is not based on one sample; instead, it is based on many samples.

Activated Alumina

A medium made by treating aluminum ore so that it becomes porous and highly adsorptive. Activated alumina will remove several contaminants including fluoride, arsenic, and selenium. It requires periodic cleaning with a regenerant such as alum, acid and/or caustic.

Activated Carbon

A water treatment medium, found in block, granulated, or powdered form, which is produced by heating carbonaceous materials, such as coal, wood, or coconut shells, in the absence of air, creating a highly porous adsorbent material. Activated carbon is commonly used for dechlorination, organic chemical reduction and radon reduction, and is recognized by the US EPA as the best available technology for reduction of organic chemicals from drinking water.

Adsorption

The physical process occurring when liquids, gases, or suspended matters adhere to the surfaces of, or in the pores of, an adsorbent media such as activated carbon. Adsorption is a physical process which occurs without chemical reaction.

Aeration

The process in which air is brought into intimate contact with water, often by spraying water through air, or by bubbling air through water. Aeration may be used to add oxygen to the water for the oxidation of matter such as iron, or to cause the release of dissolved gases such as carbon dioxide or hydrogen sulfide from the water.

Aggressive Water

A term usually applied to waters containing acid or oxygen which hasten corrosion (rusting).

Algae

Plant life (green scum) containing chlorophyll is usually found in stagnant surface water. Excessive growths may create taste and odor problems, and consume dissolved oxygen during decay. Sometimes it may be controlled in a pond by the addition of Potassium Permanganate. In a water supply system, chlorination followed by dechlorination is often used.

Alkali

A substance which creates a bitter taste and a slippery feel when dissolved in water and will turn red litmus paper blue. An alkali has a pH greater than seven and is the opposite of an acid. Highly alkaline waters tend to cause drying of the skin. Alkalis may include the soluble hydroxide, carbonate, and bicarbonate salts of calcium, magnesium, potassium, and sodium. A hydroxide alkali may also be called a base.

Alkalinity

The quantitative capacity of water to neutralize an acid; that is, the measure of how much acid can be added to a liquid without causing a significant change in pH. Alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have high alkalinity. In the water industry, alkalinity is expressed in mg/l of equivalent calcium carbonate. There are three kinds of alkalinity: carbonate, bicarbonate, and hydroxide alkalinity. Total alkalinity is the sum of all three kinds of alkalinity. Different tests are used to determine the quantity of the different kinds of alkalinities present in water.

Alum

The common name for aluminum sulfate [Al2 (SO4) x 14H2 O] which is often used as a coagulant in water treatment.

Amoeba

A single celled protozoan that is widely found in fresh and salt water. Some types of amoebas cause diseases such as amoebic dysentery.

Anaerobic organism

An organism that can thrive in the absence of oxygen (air), such as bacteria in a septic tank.

Angstrom unit

A unit of wavelength of light equal to .00001 millimeter or .0001 microns.

Anion

A negatively charged ion in solution, such as bicarbonate, chloride, or sulfate. An anion [such as chloride (Cl)] may result from the dissociation of a salt, acid, or alkali.

Anion Exchange

An ion exchange process in which anions in solution are exchanged for other anions from an ion exchanger. In demineralization, for example, bicarbonate, chloride and sulfate anions are removed from solution in exchange for a chemically equivalent number of hydroxide anions from the anion exchange resin.

Aquifer

Natural underground reservoirs of porous layers of sand, rock or gravel.

Artesian

Describes underground water trapped under pressure between layers of impermeable rock. An artesian well is one that taps artesian water.

Backflow

Flow of water in a pipe or line in a direction opposite to the normal flow; often associated with back siphonage or the flow of possibly contaminated water into a potable water system.

Bacteria

Unicellular microorganisms which typically reproduce by cell division. Although usually classed as plants, bacteria contain no chlorophyll. Many different types of bacterial organisms are often found in drinking water. Most municipally treated water is essentially bacteria free due to the addition of chlorine. Some forms of cyst type viruses have a degree of immunity to chlorine due to the cocoonlike shell around the virus. These types of organisms such as Giardia Cyst, Giardia Lamblia, and Cryptosporidium have a physical size of three to seven microns and can be effectively removed by submicron filtration. Some bacteria are helpful to man, others harmful.

Bacteriastatic

Having the ability to inhibit the growth of bacteria without destroying them. For example, silver impregnated activated carbon will limit bacterial colonization but not eliminate it. Bactericide Any substance or agent which kills bacteria.

Brackish Water

Water containing bacteria between 1.000 and 15,000 ppm of dissolved solids.

Capacity

In a softener or deionizer it is the adsorption activity possessed in varying degree by ion exchange materials. This quality may be expressed as kilograins per cubic foot, gram milli equivalents per gram, pound equivalents per pound, gram milli equivalents per milliliter, etc., where the of these ratios represent the weight of the ions adsorbed and the denominators, the weight or volume of the adsorbent. It can also refer to the ability of any media to take up a specific contaminant and is rated by time over gallons. As to flow rates, it is the maximum or minimum flow obtainable under given conditions of media, temperature, pressure, velocity, etc.

Carbonaceous Exchangers

Ion exchange materials of limited capacity prepared by the sulfonation of coal, lignite, peat, etc.

Carbon Dioxide

Water with a low pH value usually contains free carbon dioxide. Its presence is caused generally by absorption of carbon dioxide (CO2) from the air as water falls as rain, or by decay of organic matter in the earth. Well water containing substantial quantities of CO2 has a resultant low pH and corrosive qualities. Carbon dioxide in water forms a weak carbonic acid.

Carcinogen

A substance that can cause cancer.

Chloramines

Chemical complexes formed from the reaction between ammonia and chlorine being used to disinfect many municipal water supplies. Does not combine with organics to form triclomethanes.

Chlorinator

A mechanical device specifically designed to feed chlorine gas or pellets, or solutions such as hypochlorides, into a water supply in proportion to the flow of water.

Chlorine

Widely used in the disinfection of water and as an oxidizing agent for organic matter, iron, hydrogen sulfide, etc. It is available as a gas, as a liquid in sodium, hypochlorite, or as a solid in calcium hypochlorite. In water chlorine reacts with organics to form trihalomethanes (THM) which can cause cancer.

Chlorine Demand

A measure of the amount of chlorine which will be consumed by organic matter in a water before a chlorine residual will be found.

Coagulant

A material such as alum, which will form a gelatinous precipitate in water, and gather finely divided particles into larger ones which can then be removed by settling and/or filtration.

Coliform Bacteria

A group of organisms primarily found in human and animal intestines and wastes, and thus widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic (disease producing) bacteria.

Colloid

Very finely divided solid particles larger than molecules but small enough that they will not settle out of a solution; intermediate between a dissolved particle and a suspended solid which will settle out of solution. Typically between 0.1 and 0.001 microns in diameter, it usually requires coagulation prior to filtration. Colloidal (heme) iron may be removed by special anion resin.

Cryptosporidium

A waterborne protozoan that forms cysts and causes acute illness in humans. This type of organism is resistant to chlorine and ultraviolet light but can be removed by one micron filtration.

Dechlorination

The removal of excess or free chlorine from a water supply by adsorption with activated carbon or by catalytic type filter media.

Degassing

The removal of dissolved gasses from water such as carbon dioxide, methane, hydrogen sulfide, and oxygen. This can by done by subjecting the water to below atmospheric pressure, or by passing air through the water at atmospheric pressure.

Deionization

The removal of the ionized minerals and salts (both organic and inorganic) from a solution by a twophase ion exchange procedure. First, positively charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. The term is often used interchangeably with demineralization. The cation resin is regenerated with an acid and the anion resin is regenerated with sodium hydroxide (caustic soda).

Desalination

The removal of dissolved inorganic solids (salts) from a solution such as water to make it free of dissolved salts. Typically accomplished by reverse osmosis.

Dwell Time

The period of time that water is held in contact with, treated by or let to stand in one place.

E. coli (Escherichia coli)

A type of Coliform bacteria that is associated with human and animal fecal waste.

Effluent

The outflow of a water treatment device. Sometimes used to mean the product water of a given water conditioning device or system. , distillation, or electrodialysis.

Exhaustion

The state of the adsorbent such as activated carbon, a water softener, or a deionizer that is no longer capable of the removal of a specific pollutant or of useful ion exchange. The exhaustion point is determined arbitrarily in terms of: (a) the presence or increase of an adsorbent contaminant as chlorine; (b) a value in parts per million of ions in the effluent solution; (c) the reduction in quality of the effluent water determined by a conductivity bridge which measures the resistance of the water to the flow of an electric current.

Ferric Iron

Small solid iron particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide (Fe2O3), which are suspended in water and visible as "rusty" water. Ferrous (iron in solution) is readily converted to ferric iron by exposure to oxygen found both in water and air. Ferric iron can by removed by filtration, but not by ion exchange.

Ferrous Iron

Usually ferrous hydroxide which when dissolved in water produces a clear solution. Often called clear water iron, it can be removed by ion exchange.

FiloxR

A naturally occurring ore which serves as a catalytic filter media in the removal of iron, hydrogen sulfide and manganese. It normally requires only backwashing, but the use of oxidizers such as chlorine or potassium permanganate enhances its action.

Filter

A device used to clean water by removing iron, silt, taste, odor, color, etc., before it is fed into the softener or supply lines of the consumer. Includes mechanical, adsorptive, oxidizing and neutralizing filters. Available as media beds in tanks or as cartridge type devices

FilterAg

The tradename for aluminum silicate (pumicite) granular product used as a general purpose filter medium. Lighter in weight, it requires a lower backwash rate. Typically removed suspended solids down to the 2040 micron range.

Filtration

The process of passing water through a porous substance to remove solids in suspension. Available as media beds in tanks or as cartridge type devices

Flash Distillation

A distillation process in which hot water is introduced into a low pressure chamber causing some of the water to flash or quickly turn to steam.

Flocculants

Materials added to water which can cause gelatinous clouds of precipitate to enclose fine particles of foreign material in order to settle or filter them from the water.

gpg

grains per gallon A unit of water hardness. One grain per gallon is equal to 17.1 parts per million.

Greensand

A natural mineral, primarily composed of complex silicates, which possess ion exchange properties. Greensand was the original material used in domestic and commercial water softeners and is the base product in the production of manganese greensand.

Groundwater

The term describing all subsurface water and the source of well water. It can be found in aquifers as deep as several miles.

Influent

The water entering a water treatment device.

Inorganic Matter

Matter which is not derived from living organisms and contains no organically produced carbon; includes rocks, minerals and metals.

Ion

An atom, or group of atoms in a solution which function as a unit, and has a positive or negative electrical charge, due to the gain or loss of one or more electrons. It is smaller than a colloid.

Ion Exchange

A reversible process in which ions are released from an insoluble permanent material in exchange for other ions in a surrounding solution; the direction of the exchange depends upon the affinities of the ion exchanger for the ions present and the concentration of the ions in the solution. The ion exchanger media is an insoluble permanent solid medium for a water filtration device.

Iodine Number

A measure of the ability of activated carbon to adsorb substances with low molecular weights. It is the milligrams of iodine that can be adsorbed on one gram of activated carbon.

Ionization

The dissociation of molecules into simpler, electronically charged particles. It is related to the gaining or losing of electrons causing the atoms to become electronically charged.

Iron

An element often found dissolved in ground water (in the form of ferrous iron) in concentrations usually ranging from zero to 10 ppm (mg/l). It is objectionable in water supplies because of the staining caused after oxidation and precipitation (as ferric hydroxide), because of tastes, and because of unsightly colors produced when iron reacts with tannins in beverages such as coffee and tea. As little as 0.3 ppm of iron can cause staining. (See also ferrous iron, ferric iron, and heme iron).

Iron Bacteria

Organisms which are capable of utilizing ferrous iron, either from the water or from steel pipe, in their metabolism, and precipitating ferric hydroxide in their sheaths and gelatinous deposits. These organisms tend to collect in pipe lines and tanks during periods of low flow, and to break loose in slugs of turbid water to create staining, taste and odor problems.

KDF

A water treatment media employing copper and zinc alloy particulates which have a redox potential. KDF does not support the growth of bacteria and lasts up to twenty times longer than activated carbon. KDF 55 granules are effective in removing chlorine and other water soluble heavy metals such as lead. KDF 85 is the choice for removing iron and hydrogen sulfide.

Macroporous

Resin Ion exchange resins produced in both cation and anion versions with 12 percent or higher cross linkage. They offer a higher resistance to oxidation and organic fouling.

Magnesium

One of the elements making up the earth's crust, the compounds of which when dissolved in water make the water hard. The presence of magnesium in water is a factor contributing to the formation of scale and insoluble soap curds.

Manganese (Mn)

A element sometimes found dissolved in ground water, usually with dissolved iron but in lower concentrations. It causes black stains in laundry and plumbing fixtures at concentrations higher than 0.05 mg/l. It is removed the same way as iron, by ion exchange or oxidation and filtration.

Manganese Greensand

Greensand which has been processed to incorporate in its pores and on its surface the higher oxides of manganese. The product has a mild oxidizing power, and is often used in the oxidation and precipitation of iron, manganese and/or hydrogen sulfide, and their removal from water. It is regenerated by the use of two to four ounces of a weak solution of potassium permanganate per cubic foot of manganese greensand.

MCL

Maximum Contaminant Level. A drinking water standard. The maximum amount of a contaminant allowed in drinking water.

MCLG

Maximum Contaminant Level Goal. The goal set for the maximum amount of a contaminant to be allowed in drinking water. Has not been approved to become the MCL.

MRDL (Maximum Residual Disinfection Level)

The highest level of disinfectant that is allowed in drinking water. The addition of a disinfectant is necessary for the control of microbial contaminants.

MRDLG (Maximum Residual Disinfection Level Goal)

The level of a disinfectant in drinking water below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

Mechanical Filter

A filter primarily designed for the removal of suspended solid particles, as opposed to filters that remove contaminants by chemical means.

Microgram per Liter

Also known as parts per billion (ppb). The common symbol for microgram per liter is µg/l.

Micron

A linear measure equal to one millionth of a meter, or .00003937 inch. The symbol for the micron is the Greek letter "µ". The smallest particle visible to the human eye is 40 microns. Most types of bacteria range from 0.05 to 10.0 microns in size.

Micron Rating

The term applied to a filter or filter medium to indicate the particle size above which all suspended solids will be removed, throughout the rated capacity. As used in industry standards, this is an "absolute", not "nominal" rating..

Milligram per Liter (mg/l)

A unit concentration of matter used in reporting the results of water and wastewater analyses. In dilute water solutions, it is practically equal to the part per million, but varies from the ppm in concentrated solutions such as brine. As most analyses are performed on measured volumes of water, the mg/l is a more accurate expression of the concentration, and is the preferred unit of measure.

Minimum Residual Disinfectant Level

The minimum level of residual disinfectant required at the entry point to the distribution system.

Mineral

A term applied to inorganic substances, such as rocks and similar matter found in the earth's strata, as opposed to organic substances such as plant and animal matter. Minerals normally have definite chemical composition and crystal structure. The term is also applied to matter derived from minerals, such as the inorganic ions found in water. The term has been incorrectly applied to ion exchangers, even though most of the modern materials are organic ion exchange resins.

ntu

Nephelometric turbidity units; Turbidity is measured with an instrument called a nephelometer. Measurements are given in nephelometric turbidity units. It is a method that you use to measure the size and concentration of particles in a liquid by analysis of light scattered by the liquid

Particulate

A term used to describe visible sediment particles, used as both singular and plural.

Parts Per Billion (ppb)

A basis for reporting the results of water and wastewater analysis, indicating the number of parts by weight of a dissolved or suspended constituent, per billion parts by weight of water or other solvent. One part per billion is equal to one microgram per liter, the preferred unit.

Parts Per Million (ppm)

A common basis for reporting the results of water and wastewater analysis, indicating the number of parts by weight of water or other solvent. In dilute water solutions, one part per million is practically equal to one milligram per liter, which is the preferred unit. 17.l ppm equals one grain per US gallon. One ppm equals one pound per million pounds of water.

pH (potential of Hydrogen)

An expression of the acidity of a solution; the negative logarithm of the hydrogen ion concentration (pH 1 very acidic; pH 14, very basic; pH 7, neutral). e.g., pH 5 is 10 times the acidity of 6 and 100 times the acidity of 7. pH is a measure of intensity and not capacity. It is the logarithm of the reciprocal of the hydrogen ion concentration of a solution. The neutral point of 7 indicates the presence of equal concentrations of free hydrogen and free hydroxide ions.

Pharmaceutical Grade Water

The definition of six grades of water by the U.S. Pharmacopoeia is as follows: 1.) Purified water 2.) Water for injection 3.) Bacteriostatic water for injection 4.) Sterile water for inhalation 5.) Sterile water for injection 6.) Sterile water for irrigation.

Point of Entry (POE)

A water treatment device which installs at the main inlet to a building and acts as centralized treatment.

Point of Use (POU)

A water treatment system designed to connect at the actual point of use for water; countertop or under sink treatment systems.

Potable Water

Water which is considered safe and fit for human consumption, culinary and domestic purposes and meets the requirements of the health authority having jurisdiction.

Powdered Activated Carbon

Activated carbon in particle sizes predominantly smaller than 80 mesh.

PPB

The abbreviation for "parts per billion". PPM The abbreviation for "parts per million".

Prechlorination

The application of chlorine to a water prior to other water treatment processes.

Precipitate

To cause a dissolved substance to form a solid particle that can be removed by settling or filtering. The term also refers to the solid thus formed.

Protozoa

Any of a large group of mostly microscopic, one celled animals living chiefly in water. Many protozoa's are parasitic and are higher on the food chain than the bacteria they eat.

Putrefaction

Biological decomposition of organic matter by microbes with the production of ill smelling products. Usually takes place when there is a deficiency of oxygen.

Radium

Naturally occurring radioactive elements such as radium 226 and radium 228 created in the decay of the uranium and thorium series. It can be removed from water by cation exchange softening.

Radon

A short lived radioactive gas produced from decaying uranium that is soluble in water. Can be effectively removed by activated carbon filtration or serration. Radon is considered carcinogenic when inhaled by humans.

Raw Water

Untreated water from wells or from surface sources or any water before it reaches a water treatment device or process.

Reverse Deionization

The use of an anion exchange unit ahead of a cation exchange unit in that order in a deionization system.

Reverse Osmosis

A process for the removal of dissolved ions from water, in which pressure is used to force the water through a semi-permeable membrane, which will transmit the water but reject most other suspended and dissolved materials. It is called reverse osmosis because mechanical pressure is used to force the water to flow in the direction that is the reverse of natural osmosis, namely from the dilute to the concentrated solution.

R.O.

The abbreviation for "reverse osmosis".

Sand Filter

A treatment device or structure for removing solid or colloidal material of a type that cannot be removed by sedimentation. Such filters can be gravity rapid rate or enclosed pressure type.

Salt

The common name for the specific chemical compound sodium chloride (NaCl), used in the regeneration of ion exchange water softeners. In chemistry, the term is applied to a class of chemical compounds which can be formed by the neutralization of an acid with a base.

Saturated Solution

A solution containing the maximum amount of the dissolved substance that such a solution can hold at this temperature.

Siliceous Gel Zeolite

A synthetic, inorganic exchanger produced by the aqueous reaction of alkali with aluminum salts.

SOC

Synthetic Organic Chemical Commercially made organic compounds, such as pesticides and herbicides.

TCE (Trichloroethylene)

A toxic volatile organic chemical typically used as an industrial solvent. TDS The abbreviation for "total dissolved solids".

Tannin

A naturally occurring substance in wood, grape skins seeds and stems. Is primarily responsible for the basic "bitter" component in wines. Acts as a natural preservative, helping the development and, in the right proportion, balance of the wine. Considered a pollutant when present in excess.

Total Coliform

Coliforms are bacteria that are naturally present in the environment. Their presence in drinking water may indicate that other potentially harmful bacteria are also present.

THAAs

Total Haloacetic Acids A group of chemicals known as disinfection byproducts. These form when a disinfectant reacts with naturally occurring organic and inorganic matter in the water.

TOC

Total Organic Carbon; A measure of the carbon content of organic matter. This measure is used to indicate the amount of organic material in the water that could potentially react with a disinfectant to form disinfection byproducts.

Total Dissolved Solids

The weight of solids per unit volume of water which are in true solution, usually determined by the evaporation of a measured volume of filtered water, and determination of the residue weight. TDS is expressed as ppm per unit volume of water. An electrical conductivity test provides only an estimate of the TDS since nonconductive substances cannot be measured by electrical means.

Total Solids

The weight of all solids, dissolved and suspended, organic and inorganic, per unit volume of water; usually determined by the evaporation of a measured volume of water at 105 degrees Celsius in a preweighed dish.

Trihalomethanes (THM's)

A group of organic chemicals to known to be carcinogenic in more than trace amounts which are produced from chlorination. They reduce the germicidal activity of chlorine in alkaline water.

TTHMs

Total Trihalomethanes A group of chemicals known as disinfection byproducts. These form when a disinfectant reacts with naturally occurring organic and inorganic matter in the water.

Treatment

Technique A required process intended to reduce the level of a contaminant in drinking water.

Turbidity

A measure of the clarity of water related to its particle content. Turbidity serves as an indicator for the effectiveness of the water treatment process. Low turbidity measurements, such as ours, show the significant removal of particles that are much smaller than can be seen by the naked eye. A measure of the amount of finely divided suspended matter in water, which causes the scattering and adsorption of light rays. Turbidity is usually reported in arbitrary nephalometric turbidity units (NTU) determined by measurements of light scattering. NTU should not exceed 0.5 in potable water. Turbidity can protect bacteria from sterilization.

Ultrafiltration

A membrane type system that removes small colloids and large molecules from solutions. Ultrafiltration removes particles in size range between 0.002 to 0.1 micron range. The process falls between reverse osmosis and microfiltration as far as the size of particles removed is concerned.

Ultrapure Water

No standards exist describing ultrapure water though it is not considered to be sterile. It is water that has been deionized and provides high resistivity and contains no organics.

Ultraviolet Light

Radiation having a wave length shorter than 4000 angstroms (visible light) down to 100 angstroms on the border of the xray region. Ultraviolet light is used as a disinfectant.

Uranium

A radioactive metallic element found naturally in combination with other materials. Uranium 238 is the most common form.

Venturi

A tube with a tapered throat which causes an increase in velocity thus a decrease in pressure of the fluid passing through it. It is the common item used to educt or suck a regenerant into a water conditioning system.

Virus

The smallest form of life known to be capable of producing disease or infection, usually considered to be of large molecular size. They multiply by assembly of component fragments in living cells, rather than be cell division, as do most bacteria. Being parasitic infectious microbes, they are much smaller than bacteria.

Volatile Organic Compounds (VOC's)

Synthetic organic chemicals that vaporize at relatively low temperatures.

Water Conditioning

Virtually any form of water treatment designed to improve the quality of water, by neutralization, inhibition or removal of undesirable substances.

Water Hammer

The shock wave produced by the abrupt change of water flow through a piping system. Water hammer produces an instantaneous multiple increase in the pressure normal to the system. The installation of a water hammer arrestor will absorb these shock waves.

Water Softening

The reduction or removal of calcium and magnesium ions which are the principle cause of hardness in water.

Xylene

A volatile organic chemical (VOC) commonly used in industry as a solvent.

Zeolite

Naturally occurring or synthetic hydrated sodium alumina silicate with ion exchange properties. Zeolites have been largely replaced with synthetic organic cation ion exchange resins. Modified Zeolites can be selectively charged with exchange minerals such as potassium and used to remove undesirable elements such as iron, hydrogen, sulfide, and manganese.

Zero Soft

Water with a total hardness less than 1.0 grain per US Gallon (17.1 ppm), as calcium carbonate.