Water Glossary: S

saline intrusion The saltwater infiltration of freshwater aquifers in coastal area when groundwater is withdrawn faster than it is being recharged
salinity The scaling or white deposits that accumulate on coffee pots, water heaters, and plumbing fixtures resulting from dissolved mineral salts in the water. Also known as total dissolved solids or TDS.
sediment Insoluble material suspended in water that consists mainly of particles derived from rocks, soil, and organic materials; a major nonpoint source pollutant to which other pollutants may attach
source water The supply of water for a water utility. Source water is usually treated before distribution to consumers, but some groundwaters are of such a quality that they can be distributed untreated. This term is preferred over raw water.*
specific conductance A measure of the ability of a solution to conduct electrical current. Its value is inversely proportional to the solution's electrical resistance. The conductivity value is commonly used in water-desalting processes as a means to evaluate desalting efficiency and to estimate the total dissolved solids concentration; the conductivity value of a water sample is multiplied by an empirical factor representative of the typical total dissolved solids/conductivity ratio for the specific type of water. The units of conductivity are often reported as micromhos per centimetre at 25° Celsius, but this is not a Système International unit; multiplying such a value by 10-4 converts the value to units of siemens per meter.*
standard (1) A recommended practice in the manufacturing of products or materials or in the conduct of a business, art, or profession. Such standards may or may not be used as (or called) specifications. (2) A document that specifies the minimum acceptable characteristics of a product or material, issued by an organization that develops such documents (e.g., an American Water Works Association standard). (3) A numerical contaminant limit set by a regulatory agency (e.g., a US Environmental Protection Agency maximum contaminant level).*
sulfate (SO42-) An inorganic ion that is widely distributed in nature. It may be present in natural waters in concentrations ranging from a few to several thousand milligrams per liter.*
surface runoff Water flowing along the ground into rivers, lakes, and oceans.
surface water All water, fresh and salty, on the Earth's surface.
SWRCB state Water Resources Control Board. Regulates water quality and water rights to protect beneficial water use in the Bay/Delta estuary.
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*Reprinted from The Drinking Water Dictionary, by permission. Copyright © 2000, American Water Works Association