calcium - One of the principal elements in the earth's crust. When dissolved, in water, calcium is a factor contributing to the formation of scale and insoluble soap curds which are a means of clearly identifying hard water.
calcium hypochlorite - A chemical compound, [Ca(Cl 0)24H2O], used as a bleach and as a source of chlorine in water treatment; specifically useful because it is stable as a dry powder and can be formed into tablets.
capacity - An expression of the quantity of an undesirable material which can be removed from water by a water conditioning medium, i.e., cleaning, regeneration or replacement, as determined under standard test conditions. For ion exchange water softeners, the capacity is expressed in grains of hardness removed between successive regenerations and is related to the pounds of salt used in regeneration. For filters, the capacity may be expressed in the length of time or total gallons delivered between servicing.
capacity curve - A graph of the capacity versus regenerant levels for an ion exchange unit or system.
capillary action - A phenomenon in which water or many other liquids will rise above the normal liquid level in a tiny tube or capillary, due to attraction between molecules of the liquid for each other and the walls of the tube.
carbonate - The CO32 ion.
carbonate alkalinity - Alkalinity due to the presence of the carbonate ion (CO32).
carbonate hardness - Hardness due to the presence of calcium and magnesium bicarbonates and carbonates in water; the smaller of the total hardness and the total alkalinity. (See temporary hardness.)
carbon dioxide - A gas present in the atmosphere and formed by the decay of organic matter; the gas in carbonated beverages; in water it forms carbonic acid.
cartridge - Any removable preformed or prepackaged component containing a filtering media or ion exchanger.
cathodic protection - A corrosion control system in which the metal to be protected is made to serve as a cathode, either by the deliberate establishment of a galvanic cell or by impressed current. (See anode.)
cation - An ion with a positive electrical charge. Calcium, magnesium and sodium are cations.
cation exchange - Ion exchange process in which cations in solution are exchanged for other cations from an ion exchanger.
caustic - Any substance capable of burning or destroying animal flesh or tissue. The term is usually applied to strong bases.
caustic soda - The common name for sodium hydroxide.
channeling - The flow of water or other solution through a limited number of passages in a filter or ion exchanger bed, instead of distributed flow through all passages in the bed. May be due to fouling of the bed and plugging of many passages, poor distributor design, flow rates which are too low, faulty operational procedures, or other causes.
chlorides - Salts of chloride are generally soluble. High concentrations contribute to corrosion problems.
chlorine - A gas, C2, widely used in the disinfection of water and an oxidizing agent for organic matter, iron, etc.
chlorinator - A device designed to feed chlorine gas or solutions of its compounds, such as hypochlorite, into a water supply.
chlorine demand - A measure of the amount of chlorine consumed by oxidizable substances in a water before a chlorine residual will be found.
coagulant - A material, such as alum, which will cause the agglomeration of finely divided particles into larger particles which can then be removed by settling and/or filtration.
coagulation - The process in which very small, finely divided solid particles are agglomerated into larger particles.
Coliform bacteria - A group of microorganisms used as indicators of water contamination, and the possible presence of pathogenic (disease producing) bacteria.
color - The shade or tint imparted to water by substances in true solution, and thus not removed by mechanical filtration; most commonly caused by dissolved organic matter, but may be produced by dissolved mineral matter. As measured in a water analysis, only the intensity of yellow color is reported.
column operation - The process in which the solution to be treated is passed through a bed, or column (as in a tank), of filter media or ion exchanger; may be either upflow or downflow.
combined available chlorine - The chlorine present as chloramine or other chlorine derivatives in a water, but still available for disinfection and the oxidation of organic matter. Combined chlorine compounds are more stable than free chlorine forms, but are somewhat slower in disinfection action.
conductance - In water conditioning, the readiness of water to carry electricity; the reciprocal of electrical resistance. The unit of measure for conductance is the mho (reciprocal ohm). Used to approximate the dissolved solids content of water. (See conductivity, resistance, specific conductance.)
conductivity - The quality or power to carry electrical current; in water; related to the concentration of ions capable of carrying electrical current. (See conductance, electrolyte.)
contamination - The presence of foreign matter in a substance which reduces the value of the substance, or interferes with its intended use.
corrosion - The disintegration of a metal by electrochemical means.
Crenothrix polyspora - A genus of filamentous bacteria which utilize iron in their metabolism, and cause staining, plugging and taste and odor problems in water systems. (See iron bacteria.)
Cryptosporidium - A common intestinal parasite found in waters contaminated by sewerage or runoff containing animal waste. It causes diarrhea, nausea, and cramps. Individuals with weakened immune systems are at particular risk. Although resistant to chlorine and most oxidizing agents, it is effectively removed by filtration to 1 micrometer, and can be destroyed by boiling.
cube - A slang expression sometimes used to mean a cubic foot of ion exchanger or filter media.
cubic foot - The volume of a cube whose sides have the length of one foot. The common basis for the measurement of the volume of ion exchangers or loose filter media.
cycle - A series of events or steps which ultimately lead back to the starting point, such as the exhaustion-regeneration cycle of an ion exchange system.
