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Wisconsin Water Quality
493
Utilities in database
4.1M
Residents served
38%
On private wells
3
Key contaminants tracked
Drinking Water in Wisconsin
Wisconsin has 493 community water systems serving approximately 4.1 million residents. Primary water sources include groundwater. The most commonly reported contaminants include arsenic, lead, disinfection byproducts. 38% of Wisconsin residents rely on private wells. DNR holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in Wisconsin
401–425 of 493Argyle Waterworks
WI1330068 · 823 served
Footville Waterworks
WI1540125 · 816 served
Pepin Waterworks
WI6470141 · 816 served
Blanchardville Waterworks
WI1330071 · 810 served
Westport Water Utility
WI1132442 · 800 served
Pittsville Waterworks
WI7720112 · 800 served
Elmwood Waterworks
WI6480250 · 798 served
Stoddard Waterworks
WI6630262 · 793 served
Plain Waterworks
WI1570098 · 792 served
Friendship Waterworks
WI7010110 · 781 served
Cassville Waterworks
WI1220091 · 777 served
Alma Waterworks
WI6060192 · 769 served
Wyocena Waterworks
WI1110124 · 768 served
Cambria Waterworks
WI1110041 · 767 served
Coon Valley Waterworks
WI6630252 · 765 served
Clayton Waterworks
WI6490334 · 765 served
Mercer Sanitary District
WI8260120 · 760 served
Wonewoc Waterworks
WI7290137 · 758 served
Whitelaw Waterworks
WI4360439 · 757 served
Lake Meadows Water Trust
WI2680228 · 750 served
Glidden Sanitary District
WI8020376 · 750 served
Wabeno Sanitary Dist 1
WI7210110 · 750 served
Tigerton Waterworks
WI4590462 · 740 served
Mellen Water Utility
WI8020378 · 731 served
Coleman Waterworks
WI4380436 · 727 served
Key Contaminant Concerns in Wisconsin
Lead
Lead is a naturally occurring heavy metal that was widely used in plumbing infrastructure until it was banned for new installations in 1986. An estimated 9.2 million lead service lines still connect homes to public water mains across the United States, along with millions of homes with lead solder in their internal plumbing.
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
Arsenic
Arsenic (As) occurs naturally in rock and soil, dissolving into groundwater through natural weathering processes. Inorganic arsenic — the form found in drinking water — is a known human carcinogen. The western United States has particularly arsenic-rich geological formations, but elevated levels have been found in 48 states. Arsenic is tasteless and odorless.
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Data source: Utility data from EPA SDWIS. 493 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-19