USGS profiles private wells
As many as 43 million people in the U.S. get their drinking water from private wells, yet the quality of the water from those wells is largely unknown. A new report from the U.S. Geological Survey (USGS) provides a comprehensive survey of these private wells. The report also documents areas where residents may be at risk of exposure to both natural and human-made compounds and elements in groundwater. The 214-contaminant assessment includes dozens of metals; radionuclides such as radon; organic compounds, including pesticides such as atrazine; and other compounds of concern.
Leslie DeSimone and her USGS colleagues analyzed water from more than 2000 wells sampled from 1991 to 2004. Groundwater generally movesand therefore changesslowly, so levels of natural compounds should remain fairly constant, DeSimone explains. The team added to existing data for areas long known to be of high concern for arsenic, such as New England. The researchers also found in some areas detectable levels of newer human-made compounds such as methyl-tert-butyl ether (MTBE) and currently used pesticides in drinking-water wells.
"We identified microbial contaminants, which are possible indicators of sewage contamination, as one of the most frequently occurring contaminants of potential health concern," notes DeSimone. Her team detected total coliform in about one-third of 400 sampled wells, an indicator of bacteria present and possible contamination from human or animal waste from septic tanks or agricultural waste ponds.