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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
376–400 of 493Shell Lake Waterworks
WI8660304 · 950 served
Laona Sanitary Dist
WI7210108 · 950 served
Paddock Lake Waterworks
WI2300146 · 945 served
Rib Lake Waterworks
WI8610126 · 945 served
Siren Waterworks
WI8070311 · 941 served
Iron Ridge Waterworks
WI1140150 · 937 served
Dresser Waterworks
WI6490336 · 936 served
Owen Waterworks
WI6100334 · 936 served
Plainfield Waterworks
WI4700268 · 924 served
Shiocton Utilities
WI4450415 · 921 served
Milltown Waterworks
WI6490339 · 915 served
Centuria Waterworks
WI6490332 · 900 served
Lone Rock Waterworks
WI1530061 · 895 served
Elk Mound Waterworks
WI6170264 · 895 served
Montreal Waterworks
WI8260121 · 887 served
Biron Water Utility
WI7720171 · 879 served
Arena Waterworks
WI1250073 · 877 served
Brandon Waterworks
WI4200402 · 872 served
Allenton Sanitary District
WI2670104 · 860 served
Hillcrest Estates Mhp
WI6180285 · 850 served
Necedah Waterworks
WI7290130 · 844 served
Highland Waterworks
WI1250080 · 842 served
Dorchester Waterworks
WI6100326 · 834 served
Birnamwood Waterworks
WI4590449 · 832 served
Arlington Waterworks
WI1110093 · 823 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