USGS scientists evaluated a range of inorganic and organic contaminants in domestic wells from every state and Puerto Rico.
Inorganic compounds arsenic (11 percent) and nitrate (8 percent) exceeded the U.S. Environmental Protection Agency´s drinking water standards in well water most often while uranium, mercury, and fluoride also exceeded standards at a smaller percentage.
Organic compounds rarely exceeded drinking water standards; however, atrazine, metolochlor, simazine, MTBE and chloroform were all detected in more than 5 percent of the wells sampled.
Since the water quality of domestic wells is not federally regulated or nationally monitored, this study provides a unique, previously nonexistent perspective on the quality of the self-supplied drinking water resources used by 45 million Americans in the United States.
This national reconnaissance study is based on a compilation of existing data from a very large number of wells sampled as part of multiple USGS programs. The USGS is continuing this research to include a broader list of contaminants from a selected set of wells to further investigate geographic patterns and the co-occurrence of multiple contaminants. Release of this information is anticipated in 2007.
The newly released study on the chemical contamination of self-supplied domestic well water is featured in the August issue of the science journal Ground Water Monitoring & Remediation a publication of the National Ground Water Association; access this article and data from http://health.usgs.gov/.
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