Study: Arsenic may contaminate private wells

Millions of Americans who get their water from private wells may be exposed to unsafe levels of arsenic, according to research published Oct. 18 in Environmental Science & Technology.

"Based on a detailed assessment of where US geology is likely to create high levels of naturally-occurring arsenic, and where private wells are located, scientists from the U.S. Geological Survey and Centers for Disease Control estimated that around 2 million people are probably drinking it at levels higher than the legal limit of 10 parts per billion," Zoe Schlanger reports for Route Fifty.

Around 15 percent of Americans--about 43 million people--use private wells, but they're mostly unregulated. Private wells aren't covered by the Federal Safe Drinking Water Act, so government officials don't test them for contamination as they do public water systems. "Arsenic can’t be removed from water with chlorine, or by boiling," Schlanger reports. "The CDC recommends private well owners distill their water or treat it with a reverse-osmosis filter. Public water utilities have a range of options for treating their water for arsenic—from reverse osmosis to a process called 'coagulation and filtration.'"

Arsenic is naturally occurring in the earth's crust, but can also seep into water from presticide run-off or coal-fired power plants. In May, Environmental Protection Agency Administrator Scott Pruitt halted an Obama-era rule meant to lower the amount of arsenic that power plants are allowed to dump in waterways, saying it was too costly, Schlanger reports.