Wisconsin
Water quality data from the EPA Safe Drinking Water Information System
Water Systems
24,118
Active public water systems
Population Served
5.12M
Residents with piped water
Lead Violations
59
Systems exceeding 15 ppb
Copper Violations
355
Lead & Copper Rule
Average Lead Level
EPA Action Level: 15 ppb
MCLG (health goal): 0 ppb
Average across 2862 systems with reported lead data.
Violations Detected
414 water systems in Wisconsin have reported violations under the Lead and Copper Rule. These utilities are required to notify customers and take corrective action.
Water Systems: Highest Lead Levels
| System Name | City | Population | Lead Level | Status | Sample Date |
|---|---|---|---|---|---|
| WEST BEND | 31,752 | 23.00 ppb | Violation | 2025-06-30 | |
| ELKHORN | 10,317 | 14.00 ppb | OK | 2021-12-31 | |
| FORT ATKINSON | 12,390 | 13.00 ppb | OK | 2023-09-30 | |
| TWO RIVERS | 11,270 | 13.00 ppb | OK | 2025-09-30 | |
| BEAVER DAM | 16,200 | 11.30 ppb | OK | 2023-09-30 | |
| MILWAUKEE | 35,598 | 11.00 ppb | OK | 2018-09-30 | |
| WATERTOWN | 23,945 | 11.00 ppb | OK | 2024-09-30 | |
| LA CROSSE | 53,000 | 10.90 ppb | OK | 2025-09-30 | |
| PLATTEVILLE | 12,268 | 10.30 ppb | OK | 2025-09-30 | |
| JANESVILLE | 64,415 | 10.00 ppb | OK | 2020-10-31 | |
| NEENAH | 27,506 | 10.00 ppb | OK | 2025-09-30 | |
| WISCONSIN RAPIDS | 20,000 | 10.00 ppb | OK | 2020-10-31 | |
| Cudahy | 18,659 | 10.00 ppb | OK | 2025-06-30 | |
| WHITEWATER | 14,000 | 10.00 ppb | OK | 2023-09-30 | |
| LITTLE CHUTE | 12,168 | 8.60 ppb | OK | 2025-09-30 |
Showing top 15 of 2847 systems with lead data. Action level: 15 ppb.
Systems With Active Violations
These water systems have exceeded EPA limits and must take corrective action.
FOND DU LAC · Pop. 44,303
Lead: 7.90 ppb (2025-06-30)
WEST BEND · Pop. 31,752
Lead: 23.00 ppb (2025-06-30)
Brookfield · Pop. 29,070
Lead: 1.50 ppb (2023-09-30)
GREEN BAY · Pop. 21,133
Lead: 1.20 ppb (2023-09-30)
Onalaska · Pop. 18,000
Lead: 0.00 ppb (2023-09-30)
APPLETON · Pop. 13,024
Lead: 0.47 ppb (2023-09-30)
BARABOO · Pop. 12,703
Lead: 8.10 ppb (2023-09-30)
CEDARBURG · Pop. 11,800
Lead: 7.60 ppb (2023-09-30)
MARINETTE · Pop. 10,968
Lead: 0.93 ppb (2023-09-30)
ELKHORN · Pop. 10,317
Lead: 14.00 ppb (2021-12-31)
Sparta · Pop. 10,025
Lead: 1.40 ppb (2023-09-30)
FORT MCCOY · Pop. 10,000
Lead: 8.00 ppb (2024-09-30)
Water Source Types
Air Quality
GoodAvg AQI
43.9
PM2.5
5.7 µg/m³
Unhealthy Days
3
Primary Pollutant
Ozone
Source: EPA AirNow & American Lung Association 2024 State of the Air. AQI scale: 0–50 Good · 51–100 Moderate · 101–150 Sensitive Groups · 151+ Unhealthy.
PFAS Contamination
Moderate DetectionPFAS (per- and polyfluoroalkyl substances), known as “forever chemicals,” are a group of synthetic chemicals that persist indefinitely in the environment and human body. The EPA set a maximum contaminant level (MCL) of 4 parts per trillion (ppt) for PFOA and PFOS in April 2024. View national PFAS tracker →
Systems Tested
298
PFAS Detected
118
Detection Rate
39.6%
Exceeding MCL (4 ppt)
28(9.4%)
Highest recorded level: 92 ppt (EPA MCL: 4 ppt). Most widespread contamination region nationally (EWG). State has own drinking water standards. Marinette/Peshtigo area heavily affected by Tyco/Chemguard PFAS contamination