Glossary of Terms

Glossary of Terms - W

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Water that has been used.

1. (RO, ultrafiltration, electrodialysis) The stream of water (not product water) created as the result of processing water--the reject water or concentrate.

2. (ion exchange and filtration) The spent water used in the total backwash/and or regeneration cycle.

3. The used water and solids from a residence or a community (including used water from industrial processes) that flow to a septic system or a treatment plant. Storm water, surface water, and groundwater infiltration also may be included in the waste water that enters a waste water treatment plant. The term sewage usually refers to household wastes, but this word is being replaced by the term waste water.

A facility that receives waste waters (and sometimes runoff) from domestic and/or industrial sources, and by a combination of physical, chemical, and biological processes reduces (treats) the waste waters to less harmful byproducts; known by the acronyms WWTP, STP (sewage treatment plant), and POTW (publicly owned treatment works).
[H2O] An odorless, colorless, tasteless liquid which exists as ice in solid form (phase) and steam in vapor form (phase).

It freezes at 32 degrees F (0 degrees C) and boils at 212 degrees F (100 degrees C).

Water is a polar liquid with high dielectric constant which accounts for its solvent power; it is called the universal solvent.

It is a weak electrolyte; in pure water, only about two molecules in every 1,100,000,000 separate into H3O+ and OH- ions. Water is only slightly compressible.

It is the liquid that descends from the clouds as rain and forms lakes, streams, and seas (oceans). Water is a major constituent of all living matter.

Also referred to as H2O (dihydrogen oxide) and HOH (hydrogen hydroxide).

A prolific growth of plankton, including blue-green algae, which may occur and be so dense that it imparts a greenish, yellowish, or brownish color to water near the surface of a lake, pond, or reservoir.
A summation of inputs, outputs, and net changes to a particular water resource system over a fixed period.

Also, water balance model.

A flushable toilet.
Virtually any form of water treatment designed to improve the aesthetic quality of water by the neutralization, inhibition, or removal of undesirable substances. (Not health related)
See Hydrologic Cycle
The maximum density of water is reached at 39 degrees Fahrenheit (4 degrees Centigrade). It becomes less dense at both higher and lower temperatures.
A process in underground mining such as oil recovery in which oil or a mineral from underground formations is replaced by an infusion of warm, softened water thus bringing the underground substance to the surface for recovery.

Also known as oil well flooding.

See Flux
The common name of a sodium silicate (Na2O xSiO2) substance used for corrosion control in potable waters.

It is also an ingredient used in the manufacture of synthetic gel zeolite.

A shock wave or series of waves produced by the abrupt acceleration or deceleration of water flow due to inertia. Water hammer may produce instantaneous pressures many times the normal pressure.
See Head
An outer casing which holds water or through which water flows and circulates to absorb heat and cool the interior of the mechanism or machinery that the water jacket is surrounding.
Water which has been chemically combined with a substance to form a hydrate and which can then be removed (as by heating) without essentially changing the chemical composition of the substance.
See Water Conditioning.
An agency or person that supplies water (usually potable water).
See Water Retention.
The amount of water, expressed as a percent of the wet weight of an ion exchanger, retained within the resin bead and on the surface of fully swollen and drained ion exchange media.

Also called water regain.


A compound which, when introduced into water used for cleaning or washing, will counteract the effects of the hard water minerals (calcium and magnesium) and produce the effect of softened water. For example, detergent additives and polyphosphates.


A pressurized water treatment device in which hard water is passed through a bed of cation exchange media (either inorganic or synthetic organic) for the purpose of exchanging calcium and magnesium ions for sodium or potassium ions, thus producing a softened water which is more desirable for laundering, bathing, and dishwashing.

This cation exchange process was originally called zeolite water softening or the Permutit Process. Most modern water softeners use a sulfonated bead form of styrene/divinylbenzene (DVB) cation resin.

Salt suitable for regenerating residential and commercial cation exchange water softeners. Most commonly used for this purpose is sodium chloride (NaCl) in crystal or pelletized form. Rock grade salt should be 96-99 percent NaCl; evaporated salt should be 99+ percent NaCl.

Potassium chloride (KCl) may also be used for the regeneration cycle in the cation exchange process, thus minimizing the amount of sodium added to both the softened water and the spent regenerant water going to the drain.

The removal of calcium and magnesium, the ions which are the principal cause of hardness, from water.
The maximum concentration of a chemical compound which can result when it is dissolved in water. If a substance is water soluble, it can very readily disperse through the environment.
The basic origin of a water, either a surface source (such as a lake, river, or reservoir) or a subsurface source (such as a well). After treatment and pumping via pipe lines, the treated and pumped water becomes a water supply.
Cloudy milk-like film, spots, streaks, or heavy white deposits left on surfaces after water has dried from them, especially noticeable on clear glassware and cars after washing.

Spotting is caused by minerals that had been dissolved in the water remaining behind after the water has evaporated away.

Soft water spotting can be wiped off easily with a damp cloth or rinsed off with a little fresh water. Hard water deposits, on the other hand, are comprised of the more tenacious calcium and magnesium salts. Hard water films typically require harsh abrasives or an acid cleaner to remove them.

A third type of water residue film is due to silica (SiO2) deposits. Silica spotting is rare, but it is more difficult or impractical to be removed when it does occur.

If glassware films won't dissolve in acids such as vinegar or lemon juice, they may be due to silica spotting or etching. If the spot won't dissolve in acid, but can be scratched off with a razor blade or pinpoint, it's likely a silica film.

An impound for liquid wastes, so designated as to accomplish some degree of biochemical treatment of the wastes.
A person who owns or operates a public water system.
See Water Source.
The collection, treatment, storage, and distribution of potable water from source to consumer.
The level of the top of the zone of saturation in which free water exists in the pores and crevices of rocks and other earth strata.
See Water Conditioning.
An impound for liquid wastes, so designed as to accomplish some degree of biochemical treatment of the wastes.
An excavation where the intended use is for the location, acquisition, development, or artificial recharge of groundwater (excluding sandpoint wells).
A disease, caused by a bacterium or organism able to live in water, which can be transmitted by water.
The significant occurrence of acute infectious illness, epidemiologically associated with the ingestion of water from a public water system that is deficient in treatment, as determined by the appropriate local or state agency.
A paste, gel, or lotion that does not require rinsing. Waterless hand cleaners are useful when facilities for hand washing are not available and are also helpful in removing difficult soils.

Available for use from dispensers, or directly from their own containers, they are usually oil-in-water emulsions.

They are available with or without scrubbers. The scrubbers may be organic, (e.g., particles of polyethylene or polystyrene) or inorganic (pumice).

A tank (as in a domestic water well pumping system) in which too much water has accumulated and has replaced some of the air in the tank's air cushion causing a disruption in the normal pressure pattern needed for pumping and uniform water flow.
The land area that drains into a stream. An area of land that contributes runoff to one specific delivery point; large watersheds may be composed of several smaller "subsheds," each of which contributes runoff to different locations that ultimately combine at a common delivery point.
A condition existing in water treatment equipment and materials of such precision of construction and fit as to be impermeable to water unless sufficient pressure occurs to cause rupture.
A unit of power equal to one joule per second. The power of a current of one ampere flowing across a potential difference of one volt.
In ultrafiltration applications, the ratio of the initial weight of the feedwater to the weight of the reject water remaining at any time during the ultrafiltration process.
1. A dam-like wall or plate placed in an open channel and used to measure the flow of water. The depth of the flow over the weir can be used to calculate the flow rate, or a chart or conversion table may be used.

2. A wall or obstruction used to control flow (from settling tanks and clarifiers) to assure uniform flow rate and avoid short-circuiting.

Many circular clarifiers have a circular weir within the outside edge of the clarifier. All the water leaving the clarifier flows over this weir.

The diameter of the weir is the length of a line from one edge of a weir to the opposite edge and passing through the center of the circle formed by the weir.

A guideline used to determine the length of weir needed on settling tanks and clarifiers in treatment plants. Used by operators to determine if weirs are hydraulically (flow) overloaded.
A bored, drilled, or driven shaft, or a dug hole, whose depth is greater than the largest surface dimension and whose purpose is to reach underground water supplies or oil, or to store or bury fluids below ground.
Area containing one or more wells that produces usable amounts of water.
A particular well site location, as differentiated from other well site locations, that exist in the same water system.
The measurement, by on-site instruments or laboratory methods, of the quality of water in a well.
A watertight and gastight seal installed in a bore hole or well to prevent movement of fluids.
Laboratory procedures used to analyze a sample of water using liquid chemical solutions (wet) instead of, or in addition to, laboratory instruments.
A type of brine tank, so named because the saturated brine is always above the undissolved salt level, used on large commercial water softeners and older manual residential softeners.

Most automatic home-sized water softeners now use dry-salt saturator tanks.

See Also: Dry-Salt Saturator Tank Dry-Salt Saturator Tank Septic System Service Unit

Any number of tidal and nontidal areas characterized by saturated or nearly saturated soils most of the year that form an interface between terrestrial (land-based) and aquatic environments; include freshwater marshes around ponds and channels (rivers and streams), brackish and salt marshes; other common names include swamps and bogs.
A compound that increases the ability and speed with which a liquid displaces air from a solid surface, thus improving the process of wetting that surface.Wetting agents are all surfactants. They function by lowering surface and interfacial tension.

Soap and detergent surfactants serve as wetting agents in washing products, in addition to their other functions. In automatic dishwashing, nonionic surfactants are sometimes introduced into the last rinse for the purpose of maximizing drainage of water from dishes and untensils.

See Also: Alkylaryl Sulfonate Alkylbenzene Sulfonate (ABS) Emulsification

Water For Injection.

See Also: United States Pharmacopeia (USP) Hydraulic Grade Line Energy Grade Line (EGL) United States Pharmacopeia (USP) Slope Club Soda Community Water System Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water

World Health Organization.
The efficiency of a pump and motor together.

Also called the overall efficiency.

The process of taking water from a source and conveying it to a place for a particular type of use.
See Operating Pressure.
A part of the United Nations. The WHO, which is headquartered in Geneva, Switzerland, has compiled recommended standards for drinking water.