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Notice to Readers: Ground Water Awareness Week, March 13--19, 2005

Ground Water Awareness Week, held each year by the National Ground Water Association (NGWA), highlights ground water as a valuable resource and emphasizes to private well owners the importance of routine water quality testing and well maintenance (1).

Ground water is used for approximately half the U.S. drinking water supply (2). Most of that water is used by community water systems, which serve approximately 85% of the population (3). Under the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection Agency (EPA) sets maximum levels for contaminants in drinking water and requires community systems to routinely test for contaminants of public health concern.

An estimated 15% of the population (43.5 million persons) rely on private ground-water wells as their primary source of water (3). Unlike community water systems, private water wells are not regulated by EPA, and the quality of the water source for many of these wells has not been assessed. Ground-water quality can be affected by local land uses, geologic factors, and characteristics of the aquifer from which water is extracted. Possible contaminants can include manufactured contaminants (e.g., pesticides, fertilizers, and industrial chemicals), natural contaminants (e.g., arsenic, fluoride, and radionuclides) and pathogens (e.g., coliform bacteria and viruses).

Because private wells are not protected by SDWA, NGWA recommends annual well maintenance checks and water tests for coliform bacteria, nitrates, and other contaminants or water constituents of local concern (1,2). Additional information about Ground Water Awareness Week, well maintenance, and water testing is available at


  1. National Ground Water Association. Ground Water Awareness Week. Westerville, OH: National Ground Water Association; 2005. Available at
  2. US Environmental Protection Agency. Drinking water from household wells. Washington, DC: US Environmental Protection Agency; 2002. Available at
  3. US Geological Survey. Estimated use of water in the United States in 2000. Denver, CO: US Geological Survey; 2004. Available at

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This page last reviewed 3/10/2005