Wisconsin Water Quality Report
Tap water quality data for 4 cities in Wisconsin, updated 2026.
US average: 100 ppm
3 of 4 cities violation-free
4 cities tested
4 water systems tracked
Cleanest Tap Water in Wisconsin
Cities with the fewest water quality issues
Most Water Quality Issues in Wisconsin
Cities with the most violations and concerns
Water Hardness Across Wisconsin
Not sure what your hardness means? Use our Water Hardness Calculator or find the best hardness test kits.
Wisconsin Tap Water: What You Need to Know
Wisconsin has 4 tracked water utilities serving approximately 1.2M residents. The average water hardness is 187 ppm (10.9 GPG), classified as Very Hard — above the national average of 100 ppm. Hardness ranges from 38 ppm in Madison to 254 ppm in Milwaukee.
In the past 3 years, 1 of 4 cities in Wisconsin have recorded water quality violations, totaling 8 violations (0 health-based). All 4 tested cities have lead levels below the EPA action level of 15 ppb.
With very hard water on average, many Wisconsin residents may notice mineral buildup on fixtures, dry skin, or stiff-feeling hair. A shower filter for hard water can help reduce chlorine exposure, while a water softener addresses the mineral buildup directly.
Frequently Asked Questions About Wisconsin Water
Is tap water safe to drink in Wisconsin?
Most tap water in Wisconsin meets EPA standards, but 1 cities have recorded violations in the past 3 years (0 health-based). We recommend checking your specific city's report on TapWater.org and considering a home water test.
How hard is the water in Wisconsin?
Wisconsin's average water hardness is 187 ppm (10.9 GPG), classified as Very Hard. This is above the national average of 100 ppm. Hardness varies significantly by city — use our Water Hardness Calculator to check your specific area.
Which city in Wisconsin has the cleanest tap water?
Based on EPA violation data, lead testing, and water quality metrics, Milwaukee ranks as having the cleanest tap water in Wisconsin. It has zero violations in the past 3 years and lead levels well below the EPA action level.
Which city in Wisconsin has the most water quality issues?
Madison currently has the most water quality concerns in Wisconsin, with 8 violations in the past 3 years. Residents should check their city's detailed water quality report and consider using a certified water filter.
Where does Wisconsin get its water from?
The majority of Wisconsin's water systems (75%) use surface water as their primary source. Surface water comes from rivers, lakes, and reservoirs. Each city's specific source can vary — check individual city reports for details.
All 4 Cities
Sorted by population served