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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