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Notice to Readers: Ground Water Awareness Week, March 11--17, 2007

Approximately 40%--45% of the U.S. population depends on ground water for its drinking water supply (1--3). Each year, the National Ground Water Association (NGWA) sponsors Ground Water Awareness Week to highlight ground water as a valuable resource and to emphasize the importance of private well maintenance and water testing (4).

Ground water quality can be affected by local land uses, geologic factors, and integrity of water wells. Possible contaminants include disease-causing microorganisms, natural contaminants, and manufactured pollutants. Thirty waterborne-disease outbreaks affecting approximately 2,760 persons were reported to CDC during 2003--2004; seven outbreaks (23%) were associated with improperly treated or untreated ground water, two of which involved private wells (5).

Private domestic wells are not regulated by the U.S. Environmental Protection Agency, and private well owners are responsible for ensuring the water is safe. Routine annual well-maintenance checks by a qualified water-well systems contractor are recommended to help prevent water-quality problems. Routine annual water testing for coliform bacteria, nitrates and nitrites, and any contaminants of local concern also is recommended. NGWA suggests that water testing also might be considered if 1) a change in the taste, odor, or appearance of the well water occurs or if well repairs are required; 2) family members or houseguests have recurrent incidents of gastrointestinal illness; 3) an infant is living in the home; 4) a person would like to monitor the efficiency and performance of home water-treatment equipment; or 5) a person is buying a home and would like to assess the safety and quality of the existing water supply (6--9).

Additional information regarding well maintenance, water testing, and National Ground Water Awareness Week is available at and


  1. US Census Bureau. Annual estimates of the population for the United States, regions, and states and for Puerto Rico: April 1, 2000 to July 1, 2006 (NST-EST2006-01). Available at
  2. US Environmental Protection Agency. Private drinking water wells. Available at
  3. US Environmental Protection Agency. Public drinking water systems: facts and figures. Available at
  4. National Ground Water Association. National Ground Water Awareness Week: March 11--17, 2007. Available at
  5. CDC. Surveillance for waterborne disease and outbreaks associated with drinking water and water not intended for drinking---United States, 2003--2004. MMWR 2006;55(No. SS-12).
  6. National Ground Water Association. Bacteria: what do you want to know? Available at
  7. National Ground Water Association. Schedule your annual water well checkup. Available at
  8. US Environmental Protection Agency. Private drinking water wells: what you can do. Available at
  9. US Environmental Protection Agency. Drinking water from household wells. Available at

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

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Date last reviewed: 3/8/2007


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