Wisconsin Water Report Card: Worst Water Systems
The most contaminated public water systems in Wisconsin, ranked by PFAS levels, lead, and EPA violations from official EPA data.
Quick Answer
Prescott Waterworks has the highest PFAS in Wisconsin at 280 ppt (70x the EPA limit). Genoa City Waterworks has the highest lead at 129 ppb. The tables below rank the worst systems in each category so you can see how your water compares.
Highest PFAS Levels in Wisconsin
Public water systems in Wisconsin with the highest peak PFAS ("forever chemical") reading in EPA UCMR5 testing (2023-2025). The EPA enforceable limit for PFOA and PFOS is 4 ppt.
| # | Water System | Location | Peak PFAS (ppt) | Compounds | vs 4 ppt limit |
|---|---|---|---|---|---|
| 1 | Prescott Waterworks | Prescott · 4,258 served | 280 | 6 | 70x |
| 2 | Saukville Waterworks | Saukville · 4,268 served | 73 | 8 | 18x |
| 3 | Pewaukee City Water And Sewer Utility | Pewaukee · 8,671 served | 69 | 10 | 17x |
| 4 | Madison Water Utility | Madison · 272,000 served | 46.5 | 2 | 12x |
| 5 | Ellsworth Waterworks | Ellsworth · 3,304 served | 41 | 1 | 10x |
| 6 | Hudson Waterworks | Hudson · 18,558 served | 32 | 1 | 8x |
| 7 | Rib Mountain Sanitary Dist | Wausau · 6,398 served | 23 | 6 | 6x |
| 8 | La Crosse Waterworks | La Crosse · 53,000 served | 21 | 5 | 5x |
| 9 | Tomahawk Waterworks | Tomahawk · 3,180 served | 21 | 5 | 5x |
| 10 | Kewaskum Waterworks | Kewaskum · 4,309 served | 15 | 2 | 4x |
| 11 | Marshfield Utilities | Marshfield · 18,815 served | 14 | 5 | 4x |
| 12 | Sturgeon Bay Waterworks | Sturgeon Bay · 9,700 served | 13 | 2 | 3x |
Highest Lead Levels in Wisconsin
Community water systems in Wisconsin with the highest 90th-percentile lead result under the EPA Lead and Copper Rule. The EPA action level is 15 ppb; there is no safe level of lead for children.
| # | Water System | Location | Lead 90th-pctile (ppb) | vs 15 ppb |
|---|---|---|---|---|
| 1 | Genoa City Waterworks | Genoa City · 2,766 served | 129 | 8.6x over |
| 2 | Brillion Waterworks | Brillion · 3,262 served | 69 | 4.6x over |
| 3 | Thorp Waterworks | Thorp · 1,636 served | 38 | 2.5x over |
| 4 | Mineral Point Waterworks | Mineral Point · 2,487 served | 37 | 2.5x over |
| 5 | Wrightstown Waterworks | Wrightstown · 3,815 served | 29.5 | 2.0x over |
| 6 | Ripon Water Utility | Ripon · 7,716 served | 28 | 1.9x over |
| 7 | Mayville Waterworks | Mayville · 5,112 served | 27 | 1.8x over |
| 8 | Marshfield Utilities | Marshfield · 18,815 served | 27 | 1.8x over |
| 9 | Johnson Creek Waterworks | Johnson Creek · 3,318 served | 24.4 | 1.6x over |
| 10 | West Bend Waterworks | West Bend · 31,752 served | 23 | 1.5x over |
| 11 | Sturgeon Bay Waterworks | Sturgeon Bay · 9,700 served | 23 | 1.5x over |
| 12 | Lakeland University | Plymouth · 1,200 served | 21.8 | 1.5x over |
Most EPA Violations in Wisconsin
Community water systems in Wisconsin with the most health-based EPA Safe Drinking Water Act violations on record. A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.
| # | Water System | Location | Health-based violations |
|---|---|---|---|
| 1 | Waukesha Water Utility | Waukesha · 70,718 served | 155 |
| 2 | Sussex Village Hall & Water Utility | Sussex · 11,750 served | 29 |
| 3 | Pewaukee City Water And Sewer Utility | Pewaukee · 8,671 served | 24 |
| 4 | Pewaukee Village Waterworks | Pewaukee · 8,166 served | 23 |
| 5 | Tomah Waterworks | Tomah · 9,192 served | 16 |
| 6 | Elkhorn Waterworks | Elkhorn · 10,317 served | 14 |
| 7 | Winneconne Waterworks | Winneconne · 2,502 served | 14 |
| 8 | Ashland Water Utility | Ashland · 8,000 served | 12 |
| 9 | Jefferson Waterworks | Jefferson · 7,926 served | 9 |
| 10 | Hurley Waterworks | Hurley · 1,515 served | 8 |
| 11 | Genoa City Waterworks | Genoa City · 2,766 served | 7 |
| 12 | Juneau Waterworks | Juneau · 2,627 served | 7 |
How This Report Card Is Built
PFAS rankings use EPA UCMR5 monitoring (2023-2025), showing each system's peak detection above the 4 ppt EPA limit. Lead rankings use the EPA Lead and Copper Rule 90th-percentile tap results. Violation counts come from the EPA Safe Drinking Water Information System (SDWIS) and count health-based violations. Lead and violation lists are limited to community water systems serving 1,000 or more people. Figures are the most severe on record and do not necessarily reflect current treated water.
Frequently Asked Questions
What is the most PFAS-contaminated water system in Wisconsin?
In EPA UCMR5 testing (2023-2025), Prescott Waterworks in Prescott had the highest recorded PFAS level in Wisconsin at 280 ppt - about 70x the EPA's 4 ppt limit for PFOA and PFOS.
Which Wisconsin water system has the highest lead levels?
Genoa City Waterworks in Genoa City had the highest 90th-percentile lead result in Wisconsin under the EPA Lead and Copper Rule at 129 ppb - 8.6x the 15 ppb action level.
Which Wisconsin water system has the most EPA violations?
Waukesha Water Utility in Waukesha has the most health-based EPA Safe Drinking Water Act violations on record in Wisconsin, with 155 violations.
Where does the Wisconsin water report card data come from?
PFAS figures come from EPA UCMR5 monitoring (2023-2025), lead from the EPA Lead and Copper Rule 90th-percentile tap results, and violations from EPA SDWIS health-based violation records. Figures are the most severe on record and do not necessarily reflect current treated water. Check your exact address at knowyourexposure.com.
What Wisconsin Residents Should Do
- Look up your exact address at knowyourexposure.com for your system's data
- See the full Wisconsin water quality overview
- If your system is listed, a certified filter (reverse osmosis for PFAS, NSF-53 for lead) reduces exposure at the tap. See the best water filters.