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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
26–50 of 493Stevens Point Waterworks
WI7500141 · 26,717 served
Superior Water Light & Power Company
WI8160147 · 26,084 served
De Pere Waterworks Sa 1
WI4050453 · 25,660 served
Fitchburg Utility Dist 1
WI1130231 · 24,500 served
Watertown Waterworks
WI1280044 · 23,945 served
Middleton Waterworks
WI1130242 · 23,868 served
Menomonee Falls Ww - Surface Water
WI2680082 · 23,867 served
Franklin Water Utility
WI2410563 · 22,500 served
Village of Caledonia Water Utility
WI2520184 · 21,819 served
Grand Chute Tn San Dist 1
WI4450429 · 21,583 served
South Milwaukee Waterworks
WI2410144 · 21,340 served
Howard Waterworks
WI4050468 · 21,133 served
Germantown Water Utility
WI2670105 · 20,027 served
Wis Rapids Water Works & Lighting Comm
WI7720108 · 20,000 served
Marshfield Utilities
WI7720165 · 18,815 served
Cudahy Waterworks
WI2410169 · 18,659 served
Hudson Waterworks
WI6560087 · 18,558 served
Onalaska Waterworks
WI6320327 · 18,000 served
Fox Crossing Utilities West
WI4710358 · 18,000 served
Ashwaubenon Waterworks
WI4050456 · 17,730 served
Kaukauna Utilities
WI4450336 · 17,493 served
Bellevue Waterworks
WI4050459 · 16,715 served
Beaver Dam Water Utility
WI1140059 · 16,200 served
Weston Municipal Utilities
WI7370163 · 16,000 served
River Falls Waterworks
WI6480246 · 16,000 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