202 public water systems in Wisconsin were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.
23 of 202 systems had at least one sample above a 2024 federal limit; 68 had at least one PFAS found above the reporting level; 134 had none found above the reporting level.
A single sample above a 2024 limit is a measurement, not a violation. Compliance is judged on running yearly averages, and water systems have until 2029 to meet the limits. On 20 May 2026 EPA proposed giving qualifying systems until 2031 for PFOA and PFOS and removing the limits for PFHxS, PFNA and HFPO-DA; those proposals were not final when we last checked (5 Nov 2026). Counts are per system, not per person; population figures are available only for systems serving more than 25,000 people (about 2,255,989 people across those systems here). UCMR 5 was a one-time national monitoring programme (2023–2025). The results are a snapshot at the system's entry points or taps on the sample dates, not a continuous measurement and not a compliance record.
| System | People served | UCMR 5 result |
|---|---|---|
| Milwaukee Milwaukee Waterworks | 626,000 | None detected (below the reporting level) |
Pages for these are being added in stages. The data for all 202 systems is in the public dataset.
| System | People served | UCMR 5 result |
|---|---|---|
| Madison Water Utility Madison Water Utility | 272,000 | Detected, below the 2024 limit |
| Green Bay Waterworks Green Bay Waterworks | 107,369 | None detected (below the reporting level) |
| Racine Waterworks Racine Waterworks | 105,100 | None detected (below the reporting level) |
| Kenosha Water Utility Kenosha Water Utility | 99,218 | None detected (below the reporting level) |
| Appleton Waterworks Appleton Waterworks | 74,511 | None detected (below the reporting level) |
| Waukesha Water Utility Waukesha Water Utility | 70,718 | None detected (below the reporting level) |
| Eau Claire Waterworks Eau Claire Waterworks | 70,587 | Above the 2024 limit in at least one sample |
| Janesville Water Utility Janesville Water Utility | 64,415 | None detected (below the reporting level) |
| West Allis Waterworks West Allis Waterworks | 63,240 | None detected (below the reporting level) |
| Oshkosh Waterworks Oshkosh Waterworks | 63,000 | None detected (below the reporting level) |
| La Crosse Waterworks La Crosse Waterworks | 53,000 | Above the 2024 limit in at least one sample |
| Sheboygan Water Utilities Sheboygan Water Utilities | 49,931 | None detected (below the reporting level) |
| Wauwatosa Waterworks Wauwatosa Waterworks | 49,064 | None detected (below the reporting level) |
| Fond Du Lac Waterworks Fond Du Lac Waterworks | 44,678 | None detected (below the reporting level) |
| Wausau Waterworks Wausau Waterworks | 39,994 | None detected (below the reporting level) |
| Sun Prairie Utilities Sun Prairie Utilities | 39,300 | None detected (below the reporting level) |
| Beloit City of Beloit City of | 36,677 | Detected, below the 2024 limit |
| North Shore Water Commission North Shore Water Commission | 35,598 | None detected (below the reporting level) |
| Manitowoc Waterworks Manitowoc Waterworks | 34,500 | None detected (below the reporting level) |
| West Bend Waterworks West Bend Waterworks | 32,149 | Above the 2024 limit in at least one sample |
| Oak Creek Waterworks Oak Creek Waterworks | 32,104 | None detected (below the reporting level) |
| Fitchburg Utility Dist 1 Fitchburg Utility Dist 1 | 29,900 | None detected (below the reporting level) |
| Brookfield Water Utility Brookfield Water Utility | 29,070 | Detected, below the 2024 limit |
| New Berlin Water Utility New Berlin Water Utility | 27,899 | None detected (below the reporting level) |
| Neenah Waterworks Neenah Waterworks | 27,506 | None detected (below the reporting level) |