waterbycounty

Wisconsin Water Quality

Drinking water data for all 72 counties.

Avg Water Score

39.5

State Grade

F

Counties with Data

71

of 72 total

All Wisconsin Counties

CountyWater Score
Door County86.0
Milwaukee County71.5
Wood County67.5
Portage County67.3
Outagamie County66.2
Dane County65.0
Racine County63.2
Washington County63.2
Brown County62.3
La Crosse County61.5
Sheboygan County61.2
Fond du Lac County60.4
Waupaca County58.1
Rock County57.1
Chippewa County56.0
St. Croix County53.8
Eau Claire County53.6
Manitowoc County51.8
Marathon County50.7
Kenosha County49.0
Dunn County48.2
Pierce County48.2
Winnebago County47.9
Green Lake County46.4
Lincoln County46.0
Kewaunee County45.9
Calumet County45.5
Ozaukee County45.2
Barron County45.1
Sauk County44.4
Shawano County44.3
Polk County44.0
Walworth County42.7
Burnett County41.8
Waushara County40.3
Juneau County39.7
Green County39.1
Monroe County37.3
Buffalo County36.7
Oneida County36.6
Bayfield County34.3
Marinette County33.3
Douglas County33.2
Price County32.8
Richland County32.2
Dodge County31.9
Oconto County31.7
Washburn County31.1
Jackson County30.3
Trempealeau County29.1
Jefferson County28.7
Grant County27.9
Langlade County24.3
Lafayette County23.2
Columbia County22.3
Clark County22.0
Vernon County22.0
Crawford County21.1
Taylor County20.6
Vilas County20.6
Forest County20.5
Marquette County20.0
Waukesha County19.5
Iron County19.1
Sawyer County17.9
Iowa County17.1
Pepin County12.4
Rusk County12.0
Florence County10.6
Ashland County9.5
Adams County3.7
Menominee County—

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Frequently Asked Questions

Which county in Wisconsin has the best water quality?
Door County has the highest water quality score in Wisconsin at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Wisconsin has the most water violations?
Adams County has among the lowest water quality scores in Wisconsin at 3.7/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Wisconsin?
Wisconsin has an average water quality score of 39.5/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in Wisconsin water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.

Data Source

Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

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