Study: 68,000 Illinois Residents Use Well Water High in Arsenic

Illinois is among the states with the most residents who get their water from private wells with high concentrations of toxic arsenic, according to a new study by the U.S. Geological Survey and Centers for Disease Control and Prevention.

The study, published Wednesday in the journal Environmental Science and Technology, estimates that nearly 68,000 Illinois residents could be drinking water from wells with high levels of arsenic, a naturally occurring element found in soils, sediments and groundwater that can cause cancer and skin lesions after long-term exposure, according to the World Health Organization.

Researchers estimated that of the 44 million people in the contiguous U.S. who use water from domestic wells, about 2.1 million could be drinking water with high levels of arsenic. The findings highlight the importance of private well owners working with local and state officials to test and, if necessary, treat their water supplies, according to the study’s authors.

“While we’re confident our research will help well owners understand if they live in an area of higher risk for arsenic, the only way for them to be certain of what’s in their water is to have it tested,” said Joe Ayotte, a USGS hydrologist and lead author of the study, in a press release. 

This map shows estimates of how many private domestic well users in each county could be drinking water with high levels of arsenic. (U.S. Geological Survey)This map shows estimates of how many private domestic well users in each county could be drinking water with high levels of arsenic. (U.S. Geological Survey)

Using water samples from more than 20,000 private wells, researchers developed a statistical model to estimate the probability of having high levels of arsenic in wells in a specific area. Results were published in a series of maps that show population estimates by county of residents who could be drinking water high in arsenic.

According to the study, Illinois has more than a dozen counties where up to 5,000 residents get water from wells with elevated arsenic levels. Southwest suburban Will County is the only county in the state where more than 5,000 residents are estimated to consume water high in arsenic.

Households outside of urban areas typically get drinking water from a private domestic well, as opposed to being connected to a public water system.

Public water supplies are regulated by the U.S. Environmental Protection Agency, but maintenance, testing and treatment of private water supplies are the sole responsibility of the homeowner, according to the USGS. Although an estimated 44 million people in the lower 48 states get their drinking water from private wells, surveys indicate that many homeowners are unaware of basic testing measures to help ensure that their water is safe, they agency says.

The full study, “Estimating the high-arsenic domestic-well population in the conterminous United States,” can be found here.

Contact Alex Ruppenthal: @arupp aruppenthal@wttw.com | (773) 509-5623


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