Show Nav
View printable PDF    |   

May/June 2023 Issue

Also in this issue: Wisconsin Court of Appeals Discusses Governmental Immunity for Personal Injury Claims in Non-Binding Decision     |     Coordinating Private Lead Service Line Replacement Programs to Maximize Impact

State of PFAS in Wisconsin: Drinking Water Regulations and Testing Results

PFAS (perfluoroalkyl and polyfluoroalkyl substances) continue to make state and federal headlines as states promulgate drinking water standards, the EPA proposes federal standards, and Governor Evers and the Wisconsin Legislature both make PFAS a priority in their competing budgets, each allocating over $100 million to address PFAS

Buried within all of this news are positive indicators for Wisconsin’s drinking water utilities: initial testing shows most water utilities will be able to comply with even the most stringent proposed standards. 

Background on PFAS

PFAS are a large group of widely used, long lasting chemicals, components of which break down very slowly over time. They are widely used to make various types of everyday products, such as shampoo, pesticides, and non-stick cookware. Older PFAS, including PFOA and PFOS, are no longer manufactured in the United States, but are still being produced internationally in imported consumer goods. Due to their age, PFOA and PFOS are some of the most studied PFAS. Newer PFAS, including the more commonly known GenX and PFBS, have been introduced as replacements for PFOA and PFOS

Because of their widespread use and their persistence in the environment, many PFAS are found in the blood of people and animals all over the world and are present at low levels in a variety of food products and in the environment. Scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals.

Regulation of Drinking Water

At the end of last year Wisconsin established a drinking water standard of 70 ppt (parts per trillion) for PFOA and PFOS, separately and combined. As part of the new standards, all drinking water utilities are required to sample for PFOA and PFOS. The Wisconsin Department of Natural Resources (DNR) also requires any utility that has test results exceeding the Wisconsin Department of Health Services’ (DHS) recommended health-based standard of 20 ppt, separately or combined, to provide public notice of the results.

Under the federal Unregulated Contaminant Monitoring Rule (UCMR) 3, testing was conducted between 2013 and 2015 for six PFAS, including PFOS, PFOA, PFNA, PFHxS, PFHpA, and PFBS. Under the new UCMR5, published in 2021, all public water systems serving 3,300 people or more, including 196 community systems in Wisconsin, are required to monitor for 29 additional PFAS compounds. 

In March of this year and pursuant to its general directive under the Safe Drinking Water Act, the Environmental Protection Agency (EPA) announced a proposed National Primary Drinking Water Regulation (NPDWR) for six PFAS, including PFOA, PFOS, PFNA, HFPO-DA (GenX Chemicals), PFHxS and PFBS. Under an NPDWR, the EPA may establish numerical standards for a chemical, called a Maximum Contaminant Level (MCL).

Under the proposed NPDWR, the EPA has proposed MCLs of 4 ppt each for PFOA and PFOS, and a hazard index approach for any mixture of PFNA, HFPO-DA (GenX), PFHxS and PFBS. A hazard index approach evaluates the concentrations of the four PFAS to determine if they collectively exceed a unitless hazard index (HI) of 1. Individually, the hazard index essentially establishes a limit similar to a MCL (called a Health-Based Water Concentration or HBWC) of 10 ppt for GenX, 10 ppt for PFNA, 9 ppt for PFHxS, and 2,000 ppt for PFBS. However, where more than one of these chemicals is detected, individual levels lower than the HWBCs can collectively exceed the hazard index. 

Wisconsin Drinking Water Test Results

Testing of drinking water in Wisconsin for certain PFAS is well underway and the initial results are promising for the vast majority of Wisconsin drinking water utilities and their customers. Under Wisconsin’s rules, initial monitoring of PFOA and PFOS for systems serving 10,000 or more has been completed, with monitoring for systems serving between 300 and 9,999 scheduled to wrap up in June. The total number of systems that will be sampled in Wisconsin is 1,944, which includes 610 municipal community systems. 

As of May 23, 2023, 340 Wisconsin systems have reported investigative or initial compliance sample results for PFAS, including 301 municipal community systems.1 Of these 340 systems, there have been no exceedances of the 70 ppt State MCL for PFOA and PFOS. There have been only a few potential exceedances of the State Hazard Index based on DHS advisory levels.

Initial results for the other four PFAS proposed to be regulated by the federal rule are also promising, with no detects of GenX chemicals, no exceedances of the individual HBWCs for PFBS or PFNA, and only 11 systems with samples above the HBWC for PFHxS. 

Of the systems which have reported investigative and initial compliance sample results, only about 6.8% (23 out of 340) have results above one or more of the proposed federal MCLs or hazard index. This is currently better than the DNR’s projections, based on results from Michigan, that 11.5% of Wisconsin’s 1,944 systems would exceed the proposed federal MCLs. 

Taken together, the expectation is that more than 90% of all of Wisconsin’s public water systems will be able to meet the proposed federal MCLs without additional treatment.

[1] Sample results are reported by the DNR through its Public Drinking Water Data Viewer, available at These results inform the calculations made for the purposes of this article.

This newsletter is published and distributed for informational pur- poses only. It does not offer legal advice with respect to particular situations, and does not purport to be a complete treatment of the legal issues surrounding any topic. Because your situation may differ from those described in this Newsletter, you should not rely solely on this information in making legal decisions.

More from Municipal Law Newsletter