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Why are water wells a concern?
About 43 million people – approximately 15 percent of the U.S. population -- depend on private water wells for their drinking water. All private water wells use groundwater as their water sources. Private water wells are not regulated by the U.S. Environmental Protection Agency (EPA) or, in most cases, by state laws.
Potential contamination in water wells may occur naturally or result from human activity. This contamination can cause intestinal illness, reproductive problems, and neurological disorders.
Water in private wells may also contain parasites, viruses, and bacteria, including hepatitis A, giardia, E. coli, salmonella, and cryptosporidium.
In the Southwest, water wells that are near mining operations may be contaminated with acidity, corrosion, and heavy metals such as uranium. Wells that are near gas drilling operations may be contaminated with chloride, sodium, barium, and strontium.
The Centers for Disease Control and Prevention and the EPA recommend that people regularly test the water from private water wells to ensure that the water is safe to drink.
During a 15-year study, the U.S. Geological Survey (USGS) found that 23 percent of private water wells sampled contained one or more contaminants at levels higher than human health standards. The study found contaminants in well water that included radon, arsenic, uranium, nitrate, fluoride, pesticides, solvents, E. coli, iron, and manganese. High concentrations of strontium were most common in the Southwest and south-central United States.
The USGS survey included 587 water wells in Arizona, Colorado, Nevada, New Mexico, Oklahoma, and Texas.
About 40 percent of the population on the Navajo Nation does not have access to running water. In some areas, the only sources of water are windmill-driven pumps that store water in tanks. This water is not regulated or regularly tested for water quality.
These unregulated water sources are referred to as “livestock only” wells, and these words are often written on the sides of storage tanks. However, water supplies from windmills, dug wells, and developed springs are primary sources of household water in some rural areas. Some residents use unregulated water for cooking and drinking.
At some windmill water sites, people and livestock may use the same water sources. The presence of animals increases the likelihood that the water will contain bacteria.
This description is based on the information found in the Web links listed with this topic.
Web Links from MedlinePlus (National Library of Medicine)
E. Coli Infections
Disinfecting Wells After a Disaster (Centers for Disease Control and Prevention)
Is Your Well-Water Safe? (North Carolina Department of Health and Human Services) (PDF — 181.13 KB)
Private Drinking Water Wells (Environmental Protection Agency)
Private Ground Water Wells (Centers for Disease Control and Prevention)
Protect Yourself from Arsenic in Your Well Water (North Carolina Department of Health and Human Services) (PDF — 2.64 MB)
Protect Yourself from Coliform Bacteria in Well Water (North Carolina Department of Health and Human Services) (PDF — 814.01 KB)
Protect Yourself from Mercury in Your Well Water (North Carolina Department of Health and Human Services) (PDF — 826.98 KB)
Quality of Unregulated Rural Water Supplies in the Northern Navajo Nation (University of Nevada, Reno) (PDF — 7.56 MB)
Uranium in Your Well Water (Idaho Department of Health and Welfare) (PDF — 78.98 KB)
Water-related Diseases and Contaminants in Private Wells (Centers for Disease Control and Prevention)
Last Updated: October 26, 2016