Tap Water Results

Wisconsin tap water quality

1,051 community water systems serving 4.3 million people.

Data: U.S. EPA · How we read the data · How we check it

18
systems with PFAS above a federal limit
184,985
people served by them
196
systems EPA tested for PFAS
4
systems above the lead action level

PFAS: EPA's 2023–2025 testing. Lead: results from the last five years. 322 more systems have no recent lead results in EPA's database.

Water systems with PFAS above the federal limit

Based on EPA's UCMR 5 results (2023–2025) compared to the April 2024 limits, the way EPA compares them. Systems have until 2029 to comply. Largest first.

Wisconsin PFAS report: chart, rankings and data to download →

Wisconsin's own PFAS limits

Wisconsin enforces its own drinking water limits for PFAS (effective: 2026-07-01): PFOA 4 ppt, PFOS 4 ppt, PFHxS 10 ppt, PFNA 10 ppt, HFPO-DA 10 ppt. The federal limits are 4 ppt for PFOA and PFOS.

NR 809.221 Table Da (CR 25-068) adds Hazard Index MCL of 1 (HFPO-DA, PFBS, PFHxS, PFNA). MCL compliance by 2029-04-26. Replaced 2022 state PFOA/PFOS MCL.

Source: Wis. Admin. Code ch. NR 809 (Register June 2026 No. 846), checked 2026-11-14. Utility pages compare each system's EPA results with these limits. State compliance is judged on the state's own sampling.

Largest water systems in Wisconsin

Wisconsin cities and towns

Most health-based violations since 2016

All Wisconsin utilities on this site

Every Wisconsin system serving 50,000+ people or with PFAS above a federal limit, A to Z. Download all 1,051 systems as CSV.

Questions

Does Wisconsin tap water have PFAS?

EPA tested 196 community water systems in Wisconsin for 29 PFAS between 2023 and 2025. 32 had at least one regulated PFAS detected, and 18 had an entry-point average above a 2024 federal limit. Those 18 systems serve about 184,985 people (4% of people on community water in Wisconsin). Systems have until 2029 to meet the limits.

How many Wisconsin water systems have violations?

387 systems in Wisconsin had at least one health-based violation since 2016 (975 violations in total). 606 violations are currently listed as unaddressed.

Which Wisconsin water systems are over the lead action level?

4 systems had a lead 90th percentile above the 15 ppb action level in their most recent results from the last five years. Another 322 systems have no lead results in EPA's database from the last five years, including 1 whose last result was above the action level. Lead depends on each home's pipes, so a test of your own tap is the only way to know your level.

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.