Calcium  carbonate (CaCO3). A trade name for finely ground limestone, very high  in calcium carbonate, which is used to raise the pH of acidic water.

One  of the primary elements of the earth's crust commonly found in water as  a dissolved solid. The presence of calcium in water is a factor  contributing to the formation of scale and insoluble soap curds which  are means of clearly identifying hard water. It is sometimes referred to  as lime.

All  forms of water hardness and other salts are commonly expressed in terms  of calcium carbonate equivalents. This is necessary so that minerals of  varying weight can be expressed in chemically equivalent terms.

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-milliequivalents per gram,  pound-equivalents per pound, gram-milliequivalents 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.

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

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.

A substance that can cause cancer.

The  control of the electrolytic corrosion of an underground or underwater  metallic structure by the application of an electric current is such a  way that the structure is made to act as the cathode instead of anode of  an electrolytic cell.

A positively charged particle or ion.

The common name for sodium hydroxide and often used as a regenerant of anion resin in deionization systems.

The  flow of water or regenerant taking the line of least resistance through  a media bed, as opposed to the usual distributed flow through all  passages of the bed. Channeling may be due to fouling of the bed, poor  distribution design, low flow rates, or insufficient backwash.

A mechanical device designed to introduce chemicals into a water system, more or less accurately in proportion to water flow.

The  amount of matter, both organic and inorganic, in a water or wastewater  which can be oxidized by boiling with a strong oxidizing acid, and  expressed as the equivalent amount of oxygen. Often used as a membrane  of the strength of

sewage.

Resistance to chemical change which ion exchange resins must posses despite contact with aggressive solutions.

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.

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.

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.

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

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.

Those regulations which the department having jurisdiction may lawfully adopt.

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.

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.

Discoloration  of the liquid passing through a filtration or ion exchange media. It  may be flushing from the media interstices of traces of colored organic  reaction intermediates. It could indicate the presence of metallic ions,  humus, tannins, or industrial wastes.

A  calculated value based on the hardness, the magnesium to calcium ratio,  and the sodium concentration of a water. It is used to calculate the  reduction in hardness removal capacity of a softener caused by these  factors. No single method of calculation has been widely accepted.

Water which has liquefied from steam.

The  quality or power to carry electrical current; in water, the  conductivity is related to the concentration of ions capable of carrying  electrical current. The unit of measure is the mho, which is the  reciprocal of resistivity which is the microhm.

The  actual time which water remains in contact with an oxidizer,  regenerant, or water conditioning media within a water treatment system.  The amount of contact time determines the effectiveness of the system.  Also called retention time.

The  addition of any physical, chemical, biological or radiological  substance to water which reduces the value of the water, or interferes  with its intended use.

A stopcock screwed into the street water main to provide the house service connection.

The destructive disintegration of metals by electromechanical means. Corrosion of iron and steel is commonly called rusting.

The minimum depth of an adsorbent bed requited to contain the mass transfer zone.

Any  physical connection between two otherwise separated piping systems one  of which contains potable water and the other of unknown or questionable  safety, whereby flow may occur from one system to the other depending  on the pressure differential between the two systems.

The  bonding of linear polymers into a resinous product with a material such  as divenylbenzene (DVB). The degree of crosslinking is a factor of the  resin's ability to withstand chemical oxidation. Softening resin is  usually 8 percent crosslinked, but can range from 6 percent to 10  percent which is used in hot water applications.

A  complete course of ion exchange operation. For instance, a complete  cycle of cation exchange would involve: regeneration of the resin, rinse  to remove excess regenerant, exhaustion, backwash, and finally  regeneration again.

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.

Cellulose triacetate. Used to manufacture reverse osmosis membrane.