One of the principal elements making up the earth’s crust, the compounds of which when dissolved, make the water hard. The presence of calcium in water is a factor contributing to the formation of scale and insoluable soap curds which are a means of clearly identifying hard water.

A chemical that is widely used for water disinfection, for instance in swimming pools or water purification plants. It is especially useful because it is a stable dry powder and can be made into tablets.

A relatively coarse aperture filter, designed to retain a coat of filter medium on an extended surface.

An expression of the quantity of an undesirable material which can be removed by a water conditioner between servicing of the media (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 removal 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.

Water that at some point rises higher than that portion of its surface, not in contact with the solid surface. This is due to adhesion, cohesion and surface tension where later touches a solid.

Membranes about the thickness of a human hair, used for Reverse Osmosis, nanofiltration, ultrafiltration and microfiltrtion.

Soil area above the water table where water can rise up slightly through the cohesive force of capillary action.

Any dissolved pollutant that can induce cancer.

Disposable filter device that has a filter range of 0.1 micron to 100 microns.

Chemical compounds related to carbon dioxide.

Hardness of water caused by carbonate and bicarbonate by-products of calcium and magnesium.

Chemical that increases the rate of a reaction but does not take a direct part in the reaction, so that it is still intact after the reaction has taken place.

A sedimentation area designed to remove pollutants from runoff before being discharged into a stream or pond.

A site in electrolysis where cations in solution are neutralized by electrons that plate out on the surface or produce a secondary reaction with water.

A negatively charged ion, resulting from dissociation of molecules in solution.

A separation process, which uses the action of centrifugal force to promote accelerated settling of particles in a solid-liquid mixture.

Colony Forming Units. This is a measure that indicates the number of microrganisms in water.

A valve that allows water to stream in one direction and will then close to prevent development of a back-flow.

Organic compounds that have the ability to draw ion from their water solutions into soluble complexes.

The amount of oxygen (measured in mg/L) that is consumed in the oxidation of organic and oxidasable inorganic matter, under test conditions. It is used to measure the total amount of organic and inorganic pollution in wastewater. Contrary to BOD, with COD practically all compounds are fully oxidized.

Introduction of chemical contaminants into a water body.

Dissolving of rock by exposure to rainwater, surface water, oxygen, and other gases in the atmosphere, and compounds secreted by organisms.

A chemical complex that consists of chlorine and ammonia. It serves as a water disinfectant in public water supplies in place of chlorine because chlorine can combine with organics to form dangerous reaction products. In which forms chloramines exist depends on the physical/ chemical properties of the water source.

Hydrocarbons that contain chlorine. These include a class of persistent insecticides that accumulate in the aquatic food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride, and toxaphene.

An organic solvent containing chlorine atoms that is often used as aerosol spray container, in highway paint, and dry cleaning fluids.

A water purification process in which chlorine is added to water for disinfection, for the control of present microrganisms. It is also used in the oxidation of compound impurities in water.

The part of a water treatment plant where effluent is disinfected by chlorine.

The clearness of a liquid.

Destabilisation of colloid particles by addition of a reactive chemical, called a coagulant. This happens through neutralization of the charges

Liquid particles in suspension that unite to create particles of a greater volume.

Lands and waters near the coast, whose uses and ecology are affected by the sea.

Bacteria that serve as indicators of pollution and pathogens when found in water. These are usually found in the intestinal tract of humans and other warm-blooded animals.

A rating of the purity of water based on a count of coliform bacteria.

Pipes to collect and carry wastewater from individual sources to an interceptor sewer that will carry it to a treatment facility.

Matter of very small particle size, in the range of 10-5 to 10-7 in diameter.

A sewer system that carries both sewage and rain water runoff.

A series of water samples taken over a given period of time and weighted by flow rate.

Two or more different elements held together in fixed proportions by attractive forces called chemical bonds.

The totality of different substances that are left behind in a filter medium after filtration.

The amount of material dissolved in a unit of solution, expressed in mg/L.

The process of increasing the number of particles per unit volume of a solution, usually by evaporating the liquid.

Water obtained by condensation of water vapour.

The change of state from a gas to a liquid.

The amount of electricity the water can conduct. It is expressed in a chemical magnitude. Please use also our information about TDS and conductivity.

A natural or artificial channel through which fluids may be transported.

Water removed from available supplies without return to a water resources system; water used in manufacturing, agriculture, and food preparation.

The length of time a substance is in contact with a liquid, before it is removed by filtration or the occurrence of a chemical change.

Any foreign component in a substance, for example in water.

Systems that were traditionally used to collect municipal wastewater in gravity sewers and convey it to a central primary or secondary treatment plant, before discharge on receiving surface waters.

1 gpg = 17.1 ppm

Water loss in pipes and channels by leakage or evaporation.

Large tower used to transfer the heat in cooling water from a power or industrial plant to the atmosphere either by direct evaporation or by convection and conduction.

Ability of water to dissolve or break down certain substances, particularly metals.

A process that uses opposite flows across a membrane surface to minimize particle build-up.

A microorganism in water that causes gastrointestinal illness in humans. It is commonly found in untreated surface water and can be removed by filtration. It is resistant to disinfectants such as chlorine.

Decline of the oxygen rate in water, which has serious consequences for aquatic life, caused by humans.

The portion of a stream or body of water, which is moving much faster than the rest of the water. The progress of the water is principally concentrated in the current.

The length of time a filter can be used before it needs cleaning, usually including cleaning time.