The majority of private wells providing water for 450 Wisconsin homes tested positive for harmful chemicals, though mostly at low levels, according to a new study.
The analysis, published November 2, tested the wells for 44 types of per- and polyfluoroalkyl substances (PFAS). Researchers found that 71% of the wells were contaminated with 4% of the private wells containing PFAS levels that exceeded the Environmental Protection Agency (EPA)’s proposed maximum contaminant levels. Roughly 1% had PFAS levels above the state’s recommended groundwater standards. The researchers said their work is the first to sample shallow groundwater away from known PFAS contamination sites in the state. Examining well water is important because about one quarter of Wisconsin residents get their drinking water from over 800,000 private wells.
“A big takeaway is we found PFAS in the majority of wells, but at very small levels in most of those locations,” said Steven Elmore, program director of the Bureau of Drinking Water and Groundwater at the Wisconsin Department of Natural Resources (DNR). To find it at detectable levels in shallow groundwater is not surprising, he said, noting that PFAS has been found in rainwater across the country and in Lake Michigan and Lake Superior, which flank the state.
The study was a collaboration between the Wisconsin Department of Natural Resources, the University of Wisconsin – Stevens Point, and the Wisconsin State Laboratory of Hygiene through the University of Wisconsin-Madison. It was funded by the US Environmental Protection Agency.
There are over 12,000 types of PFAS, many of which cannot be detected in water using currently available tests. These so-called “forever chemicals” do not break down naturally and can leach into drinking water from industrial sites, sewage treatment plants, landfills, or certain firefighting foams. A 2022 analysis found detectable PFAS levels in about 83% of US waterways. A recent study found that exposure to some PFAS may increase thyroid cancer risk, while past research has linked the chemicals to health problems including kidney cancer, testicular cancer, and ulcerative colitis.
The companies 3M, DuPont, and others agreed to settlements over the summer that will provide communities with billions of dollars to test for PFAS and remove them from drinking water. Last month, three residents of New Milford, Connecticut filed a lawsuit alleging that the Aquarion Water Company provided water to the public that it knew was contaminated with elevated PFAS levels.
To investigate PFAS contamination in Wisconsin’s private wells, the research team contacted homeowners across the state with shallow wells that extend less than 40 feet below the groundwater level. DNR employees and university students collected samples from the wells and sent them to the Wisconsin State Laboratory of Hygiene for analysis.
The researchers also tested for artificial sweeteners, pharmaceuticals, and nitrate to help them determine if the PFAS could be traced back to septic systems. While the study could not conclude the sources of the PFAS contamination, it does provide solid data that other researchers can use for additional analyses, said Elmore.
“This certainly is going to be a data set we’re going to be talking about for years to come,” he said.
While some states, such as New Hampshire, have extensively tested their private wells for PFAS, more testing “definitely needs to be done,” said Elmore.
“When I talk to my colleagues in other states, people are at various levels. I know that one pretty consistent call is for more funding and resources for testing private wells. But I think a lot of states haven’t really tested their public wells, either,” he added, noting that Wisconsin is expected to finish testing all of its public water supplies for PFAS by the end of the year.
Testing wells for PFAS is expensive – about $500 per sample analysis, said Elmore.
“It takes some time and it takes a trained eye,” Elmore said. “It’s not as simple as putting a bit of water in a machine and having it spit out an answer. Everything’s expensive with this.”