saline water - Water containing an excessive amount of dissolved salts, usually over 5,000 mg/l.
salt - In chemistry, the term is applied to a class of chemical compounds which can be formed by the neutralization of an acid with a with a base; the common name for the specific chemical compound sodium chloride used in the regeneration of ion exchange water softeners.
scale - A deposit of mineral solids on the interior surfaces of water lines and containers, often formed when water containing the carbonates or bicarbonates of calcium and magnesium is heated.
sedimentation - The process in which solid suspended particles settle out of water, usually when the water has little or no movement. Also called "settling".
semipermeable membrane - Typically a thin, organic film which allows the passage of some ions or materials while preventing the passage of others. Some membranes will only allow the passage of cations. (See electrodialysis.) Some membranes reject most dissolved substances, but allow the passage of water. (See reverse osmosis.)
service run - That portion of the operating cycle of a water conditioning unit in which treated water is being delivered, as opposed to the period when the unit is being backwashed, recharged or regenerated.
service unit - A term sometimes applied to softeners or filters which are regenerated or backwashed at a central point, then transported to the point of use for connection to the water system. (See portable exchange.)
soap - One of a class of chemical compounds which possesses cleansing properties; formed by the reaction of a fatty acid with a base or alkali. Sodium and potassium soaps are soluble and useful, but can be converted to insoluble calcium and magnesium soaps (curd) by the presence of these hardness ions in water.
soda ash - The common name for sodium carbonate, Na2CO3, a chemical compound used as an alkalinity builder in some soap and detergent formulations to neutralize acid water, and in the lime-soda water treatment process.
sodium - An ion found in natural water supplies, and introduced to water in the ion exchange water softening process. Sodium compounds are highly soluble, and do not react with soaps or detergents.
sodium chloride - The chemical name for common salt, widely used in the regeneration of ion exchange water softeners.
sodium cycle - The cation exchange process in which sodium on the ion exchange resin is exchanged for hardness and other ions in water. Sodium chloride is the common regenerant used in this process.
soft water - Any water which contains less than 1.0 gpg (17.1 mg/l) of hardness minerals, expressed as calcium carbonate.
softened water - Any water that is treated to reduce hardness minerals to 1.0 gpg (17.1 mg/l) or less, expressed as calcium carbonate.
solution feeder - A device, such as a power driven pump or an eductor system, designed to feed a solution of a water treatment chemical into the water system, usually in proportion to flow. (See chemical feeder.)
solvent - The liquid, such as water, in which other materials (solutes) are dissolved. (See solute.)
specific gravity - The ratio of the weight of a specific volume of a substance compared to the weight of the same volume of pure water at 4oC.
spore - In general, specialized reproductive bodies or resting cells. In water bacterial "spores" resist adverse conditions which would readily destroy the parent organism.
sterilization - A process in which all living organisms are destroyed. (See disinfection.)
sulfate - In the range of 30 gpg, sulfate salts can cause laxative effects and medicinal taste. In high concentration with high calcium hardness, a white insoluble compound is formed that is difficult to remove.
sulfate-reducing bacteria - A group of bacteria which are capable of reducing sulfates in water to hydrogen sulfide gas, thus producing obnoxious tastes and odors. These bacteria have no sanitary significance, and are classed as nuisance organisms.
sulfur - A yellowish solid element. The term is also commonly used to refer to water containing hydrogen sulfide gas.
superchlorination - The addition of excess amounts of chlorine to a water supply to speed chemical reactions or insure disinfection with short contact time. The chlorine residual following superchlorination is high enough to be unpalatable, and thus dechlorination is commonly employed before the water is used.
surface-active agent - The material in a soap or detergent formulation which promotes the penetration of the fabric by water, the loosening of the soil from surfaces, and the suspension of many soils; the actual cleaning agent in soap and detergent formulations.
surface tensionThe result of attraction between molecules of a liquid which causes the surface of the liquid to act as a thin elastic film under tension. Surface tension causes water to form spherical drops, and to reduce penetration into fabrics. Soaps, detergents and wetting agents reduce surface tension and increase penetration by water.
surfactant - A contraction of the term "surface-active agent".
suspended solids - Solid particles in water which are not in solution.
synthetic detergent - A synthetic cleaning agent, such as linear alkyl sulfonate and alkyl benzene sulfonate. Synthetic detergents react with water hardness, but the products are soluble.
