Wisconsin Water Quality Report 2026
Wisconsin tap water is use filtration based on our analysis of 10 water systems serving 1,505,140 residents. The average PurityMap score is 76.1/100 (Grade: C), which is 1.8 points below the national average.
- PFAS detected in 1 of 10 cities (10%). Forever chemicals require reverse osmosis filtration.
- 3 cities have lead at or above 5 ppb. Homes built before 1986 are at highest risk.
- 10 cities (100%) have hard or very hard water (7+ GPG) which causes scale buildup and appliance damage.
- 2 cities exceed the EPA secondary TDS guideline of 500 ppm, which affects taste and may indicate elevated minerals.
- 10 cities use chloramine or have elevated chlorine residuals. Standard Brita pitchers do not remove chloramine.
We recommend an under-sink reverse osmosis system for drinking water in PFAS-affected areas of Wisconsin. RO removes 99%+ of PFAS, lead, and other contaminants. For hard water cities, add a whole-house softener.
Hard
Wisconsin is 1.8 points below the US average of 77.9/100. Hardness is 3.1 GPG above the US average of 6.3 GPG.
Cities ranked by lowest score. Click any city for the full report and filter recommendations.
| Rank | City | Score | Hardness | Lead | Key Issues |
|---|---|---|---|---|---|
| 1 | Madison | 58/100 | 15.5 GPG | 2.8 ppb | PFAS (3.4 ppt), Very Hard (15.5 GPG), TDS (545 ppm) |
| 2 | Janesville | 73/100 | 18.0 GPG | 2.5 ppb | Very Hard (18.0 GPG), TDS (630 ppm) |
| 3 | Milwaukee | 74/100 | 7.5 GPG | 9.5 ppb | Hard (7.5 GPG), Lead (9.5 ppb) |
| 4 | Green Bay | 79/100 | 7.8 GPG | 4.5 ppb | Hard (7.8 GPG) |
| 5 | Racine | 79/100 | 7.5 GPG | 6.0 ppb | Hard (7.5 GPG), Lead (6.0 ppb) |
| 6 | Appleton | 79/100 | 8.5 GPG | 3.5 ppb | Hard (8.5 GPG) |
| 7 | Oshkosh | 79/100 | 8.0 GPG | 3.5 ppb | Hard (8.0 GPG) |
| 8 | Kenosha | 79/100 | 7.2 GPG | 5.5 ppb | Hard (7.2 GPG), Lead (5.5 ppb) |
| 9 | Waukesha | 79/100 | 7.5 GPG | 4.0 ppb | Hard (7.5 GPG) |
| 10 | Eau Claire | 82/100 | 7.0 GPG | 3.0 ppb | Hard (7.0 GPG) |
How Wisconsin's 10 cities score on the PurityMap 0–100 scale:
Water quality for the most populated cities. Click any city for details.
| City | Population | Score | Hardness | Key Issues |
|---|---|---|---|---|
| Milwaukee | 595K | 74/100 | 7.5 GPG | Hard, Lead |
| Madison | 275K | 58/100 | 15.5 GPG | PFAS, Very Hard |
| Green Bay | 107K | 79/100 | 7.8 GPG | Hard |
| Kenosha | 100K | 79/100 | 7.2 GPG | Hard, Lead |
| Racine | 78K | 79/100 | 7.5 GPG | Hard, Lead |
| Appleton | 76K | 79/100 | 8.5 GPG | Hard |
| Waukesha | 72K | 79/100 | 7.5 GPG | Hard |
| Eau Claire | 69K | 82/100 | 7.0 GPG | Hard |
| Oshkosh | 67K | 79/100 | 8.0 GPG | Hard |
| Janesville | 66K | 73/100 | 18.0 GPG | Very Hard |
10 of 10 cities (100%) in Wisconsin have hard or very hard water (7+ GPG). Janesville has the hardest at 18.0 GPG. Cities: Janesville, Madison, Appleton, Oshkosh, Green Bay, Milwaukee, Waukesha, Racine. A water softener is recommended.
PFAS have been detected in 1 of 10 cities (10%) in Wisconsin. Highest: Madison at 3.4 ppt. Affected: Madison. A reverse osmosis filter is recommended.
3 cities in Wisconsin have lead at or above 5 ppb. Highest: Milwaukee at 9.5 ppb. No safe level of lead exists. Cities: Milwaukee, Racine, Kenosha.
2 cities in Wisconsin have TDS above 500 ppm. Cities: Janesville, Madison. RO effectively reduces TDS.
Where Wisconsin gets its drinking water, based on 10 water systems.
| Source Type | Cities | % of Total |
|---|---|---|
| Surface Water | 7 | 70% |
| Groundwater | 2 | 20% |
| Mixed (Ground + Surface) | 1 | 10% |
Wisconsin has both PFAS (1 cities) and hard water (10 cities). RO for drinking water + softener for whole house.
| # | City | Pop. | Score | Hardness | Lead | PFAS | TDS |
|---|---|---|---|---|---|---|---|
| 1 | Madison | 275K | 58/100 | 15.5 GPG (Very Hard) | 2.8 ppb | ⚠️ Yes (3.4 ppt) | 545 ppm |
| 2 | Janesville | 66K | 73/100 | 18.0 GPG (Very Hard) | 2.5 ppb | ✅ No | 630 ppm |
| 3 | Milwaukee | 595K | 74/100 | 7.5 GPG (Hard) | 9.5 ppb | ✅ No | 195 ppm |
| 4 | Green Bay | 107K | 79/100 | 7.8 GPG (Hard) | 4.5 ppb | ✅ No | 200 ppm |
| 5 | Racine | 78K | 79/100 | 7.5 GPG (Hard) | 6.0 ppb | ✅ No | 195 ppm |
| 6 | Appleton | 76K | 79/100 | 8.5 GPG (Hard) | 3.5 ppb | ✅ No | 290 ppm |
| 7 | Oshkosh | 67K | 79/100 | 8.0 GPG (Hard) | 3.5 ppb | ✅ No | 275 ppm |
| 8 | Kenosha | 100K | 79/100 | 7.2 GPG (Hard) | 5.5 ppb | ✅ No | 185 ppm |
| 9 | Waukesha | 72K | 79/100 | 7.5 GPG (Hard) | 4.0 ppb | ✅ No | 200 ppm |
| 10 | Eau Claire | 69K | 82/100 | 7.0 GPG (Moderate) | 3.0 ppb | ✅ No | 245 ppm |
Wisconsin has 10 utilities. Major: Milwaukee Water Works, Madison Water Utility, Green Bay Water Utility, Kenosha Water Utility, Racine Water and Wastewater Utilities.
Sources: Lake Michigan, Groundwater deep sandstone aquifer, Lake Winnebago, Eau Claire River and groundwater, Lake Michigan via Great Lakes Compact.
- EPA Safe Drinking Water Information System
- EWG Tap Water Database
- State utility Consumer Confidence Reports
- USGS regional water monitoring data
PurityMap compiles publicly available data and does not perform independent testing.
10 city water quality reports available for Wisconsin.
Eau Claire Water Quality Report
Green Bay Water Quality Report
Janesville Water Quality Report
Kenosha Water Quality Report
Madison Water Quality Report
Milwaukee Water Quality Report
Oshkosh Water Quality Report
Racine Water Quality Report
Waukesha Water Quality Report
Compare water quality reports across all 50 US states