The Wisconsin Department of Natural Resources (DNR) discussed changes to regulations on per- and polyfluoroalkyl substances (PFAS) in drinking water at a public hearing on March 4.
PFAS are synthetic chemicals used since the 1940s in industrial and consumer products. Several threats to human health have been identified because of PFAS in the water supply, such as cancer, liver and heart effects in adults and developmental and immune issues in children, all due to bioaccumulation of PFAS in the body.
Wisconsin started addressing PFAS as a problem in 2019, when it began the process of regulating water contaminants.
At the public hearing, the DNR provided information on the economic impact, requirements and additional edits to current PFAS regulation.
Under the rules of NR 809, the Maximum Contaminant Levels (MCL) are standards set to keep harmful pollutants out of the environment. For example, pollutants like PFOA and PFOS are capped off at 70 parts per trillion (ppt). It was originally proposed as 20 ppt, but was changed because of a rule approved at a 2022 Natural Resources Board meeting.
However, the new U.S. Environmental Protection Agency (EPA) rule has set enforceable MCL standards at four ppt for PFOA and PFOS. Three other PFAS chemicals, PFNA, PFHxS and HFPO-DA, have standards set at 10 ppt.
The NR 809 revision uses something the EPA calls a “Hazard Index,” which determines the danger to public health that chemicals can have. It compares chemicals from a water sample to ratios that are in accordance with their PFAS regulations.
The threat of mixing two or more PFAS can create significant health risks. The EPA has set goals of keeping the Hazard Index for mixing PFAS contaminants at one ppt, while setting MCL goals for PFOA and PFOS to zero ppt.
Setting these new goals is included in the proposed changes to NR 809. By the year 2029, the public water systems would need to consistently regulate and monitor PFAS to adhere to the new rules and implement corrective actions on public water supply to meet the new maximum contaminant level.
The revision also included guidelines for water sampling in order to ensure the amount of PFAS in the water remains below the MCL. The testing will depend on whether the water is surface water or groundwater, how many people use that water source and how much of a contaminant is found in that water supply.
Since 2013, the number of surface water and groundwater supply points in Wisconsin being tested for PFAS has doubled from approximately 100 to approximately 200. This provides that water meets EPA standards and is safer for Wisconsin residents to drink.
The DNR said in the public hearing that many systems exist that are able to remove PFAS chemicals from drinking water. Some common treatments are granular activated carbon, reverse osmosis and ion exchange systems, many of which are in use today. Other options include abandoning contaminated wells and finding new sources of uncontaminated water.
The presentation also discussed minor changes to current regulation that would incorporate evidence from the EPA into Wisconsin PFAS legislation. Changes will also clearly define pesticide, herbicide and corrosion control in more clear terms to be more accessible to the community and include provisions for lead and copper control.
Editor's note: This article was updated at 12:09 PM on April 7, 2025 to change ppm to ppt as the PFAS MCL unit.
