PFAS in Wisconsin (WI): 21 ZIPs With Samples Above EPA MCL Values
79 ZIPs tested · 21 with samples above federal MCL levels (27%)
Data: EPA UCMR 3/5, SDWIS, ECHO, DOD
ZipCheckup's PFAS reading for Wisconsin: 21 of 79 tested ZIP codes (27%) are linked to water systems with a UCMR result above the value of an EPA PFAS MCL, with compliance required from 2029. Separately, the state has 38 Superfund sites (not screened for PFAS) and 3 military sites in Department of Defense PFAS investigations.
In Wisconsin, 27% of ZIP codes with PFAS sampling records are mapped to a water system with at least one sample above an EPA PFAS MCL value (compliance required from 2029). Our records list 38 Superfund sites and 3 military bases in the state; these are potential PFAS source types, not confirmed sources. Testing your water for PFAS is recommended.
PFAS Contamination Overview
79 ZIP codes in Wisconsin have been tested for PFAS (per- and polyfluoroalkyl substances). Of those, 21 (27%) are linked to a water system with a UCMR sample above the value of an EPA PFAS MCL set in 2024 (MCL compliance is based on running annual averages and is required from 2029).
An additional 809 ZIP codes in Wisconsin have not been tested for PFAS, representing potential undetected contamination.
Key PFAS Statistics
| Metric | Value |
|---|---|
| ZIP codes tested | 79 |
| Exceeding EPA limits | 21 (27%) |
| Superfund sites | 38 |
| Military bases with PFAS | 3 of 12 |
| Testing coverage | 9% of state ZIP codes |
| Untested ZIP codes | 809 |
PFAS Contamination Sources
Military Bases
3 military bases in Wisconsin are linked to PFAS contamination, primarily from the use of aqueous film-forming foam (AFFF) in firefighting training exercises. These foams contain high concentrations of PFOS and PFOA.
Superfund Sites
Wisconsin has 38 Superfund sites that may contribute to PFAS contamination through industrial waste, landfill leachate, and chemical manufacturing.
Other Sources
Beyond military and Superfund sites, PFAS contamination in Wisconsin also stems from:
- Industrial facilities and manufacturing plants
- Airports (AFFF use in fire training)
- Wastewater treatment plants
- Landfills (leachate from consumer products)
- Agricultural use of biosolids
What You Can Do
If your ZIP code shows PFAS contamination:
- Test your water — request a PFAS test from your utility or use a certified lab ($200-$400)
- Install filtration — reverse osmosis (RO) or activated carbon systems can reduce many PFAS; removal varies by compound and product, so choose one certified for the compounds of concern
- Check NSF certification — look for an NSF/ANSI 53 or 58 certification that names PFAS reduction (for example PFOA and PFOS)
- Monitor utility reports — under EPA's 2024 PFAS rule, public water systems must complete initial PFAS monitoring by 2027 and report results in their annual water quality reports
- Avoid contaminated sources — if on a private well near a known contamination source, test regularly
Data Sources
- PFAS detections: EPA Unregulated Contaminant Monitoring Rule (UCMR 3/5)
- Military bases: Department of Defense PFAS Task Force
- Superfund sites: EPA Superfund PFAS
Updated as new testing data becomes available.
Worried about PFAS in your water?
PFAS contamination varies by location. Enter your ZIP code to check PFAS testing results and contamination sources near you.
Check PFAS in Your ZIP Code →Frequently Asked Questions
Is there PFAS contamination in Wisconsin?
79 ZIP codes in Wisconsin have PFAS (per- and polyfluoroalkyl substances) sampling records from the water systems serving them. 21 ZIP codes (27%) are linked to a sample above the level of a federal PFAS MCL with compliance required from 2029. PFAS contamination comes from military bases, industrial sites, and consumer products.
How many ZIP codes in Wisconsin are linked to PFAS samples above federal MCL levels?
21 of 79 ZIP codes in Wisconsin with PFAS sampling records are linked to a sample above the level of a federal PFAS MCL with compliance required from 2029 (27% of those ZIP codes). 809 ZIP codes have no PFAS sampling records in this dataset.
What are the sources of PFAS in Wisconsin?
Potential PFAS source types in Wisconsin include military bases that used AFFF firefighting foam, industrial facilities, airports, and wastewater treatment plants. Our records list 3 such military bases and 38 Superfund sites in the state; a listing alone does not confirm a PFAS source.
How can I remove PFAS from my drinking water?
Reverse osmosis (RO) systems and granular activated carbon (GAC) filters can reduce some PFAS, but performance varies by product. Filters certified to NSF/ANSI 53 or 58 specifically for PFOA/PFOS reduction can reduce those compounds. Whether you choose a pitcher filter or a point-of-use RO system, check that it is certified for the PFAS in question and maintain it as directed.
What EPA drinking-water standards apply to PFAS?
In 2024 the EPA finalized national drinking water standards: MCLs of 4 parts per trillion (ppt) for PFOA and PFOS individually, individual MCLs for PFHxS, PFNA, and HFPO-DA, and a Hazard Index MCL for mixtures of PFHxS, PFNA, HFPO-DA, and PFBS. Public water systems must comply by 2029.