Four jugs of water
Five-gallon jugs of water are stored in the home of Jim Boisen and Margie Walker in the town of Campbell, Wis., in this July 20, 2022, photo. The water was provided by the city of La Crosse and the state of Wisconsin to replace drinking water contaminated with PFAS. (Coburn Dukehart / Wisconsin Watch)
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Wisconsin Watch readers have submitted questions to our statehouse team, and we’ll answer them in our series, Ask Wisconsin Watch. Have a question about state government? Ask it here.

Question: “What roles do different levels of government play in regulating carcinogens in drinking water?”

Wisconsin’s more than 11,200 public water systems are subject to federal and state drinking water rules that limit the presence of contaminants, some of which are considered carcinogenic.

Yet not all carcinogens are equally regulated in drinking water. Some have no safe level of exposure, while others are tolerated within certain thresholds. To complicate the issue, not all regulated drinking water contaminants that can cause illness, such as microbes, are carcinogenic.

The U.S. Environmental Protection Agency established national drinking water standards through the Safe Drinking Water Act, with which public water systems — utilities that serve at least 15 connections or 25 people or more for at least 60 days per year — must comply. The law also created monitoring, testing and reporting requirements.

The law sets limits on more than 90 drinking water contaminants. For example, the maximum limit of arsenic, an odorless and tasteless element that can enter drinking water from natural and human sources and is linked to several cancers, is 0.01 milligrams per liter.

States can establish their own standards if they are more restrictive or if no federal rule exists, as is the case for toxic “forever chemicals” known as PFAS. Federal regulations also can establish a treatment method the water must receive to comply with standards.

Public water systems must monitor their water and report testing data. The Wisconsin Department of Natural Resources, which oversees the state’s drinking water program, publishes results on its website here

The EPA does not regulate private wells, however. The 1.8 million Wisconsinites who use them, roughly one-third of residents, bear responsibility for testing and treating their own water for contaminants.

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Bennet Goldstein reports on water and agriculture as Wisconsin Watch’s Report for America representative on the Mississippi River Basin Ag & Water Desk — a collaborative reporting network across the Basin. Before this, Goldstein was on the breaking news team at the Omaha World-Herald in Nebraska. He has spent most of his career at daily papers in Iowa, including the Dubuque Telegraph Herald. Goldstein’s work has garnered awards, including the Associated Press Media Editors award for an explanatory feature about a police shooting in rural Wisconsin, and an Iowa Newspaper Association award for a series that detailed the impacts of the loss of social safety net programs on Dubuque’s Marshallese community. He holds a master’s degree from the University of Wisconsin-Madison.