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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
351–375 of 493Rio Waterworks
WI1110111 · 1,095 served
Greenwood Waterworks
WI6100328 · 1,079 served
Turtle Lake Waterworks
WI6030142 · 1,073 served
Dickeyville Waterworks
WI1220094 · 1,069 served
Robert William Park Water Association Inc
WI2410589 · 1,065 served
Hustisford Waterworks
WI1140148 · 1,063 served
Clear Lake Waterworks
WI6490335 · 1,061 served
Oakfield Waterworks
WI4200475 · 1,058 served
Mosinee East System
WI7372480 · 1,046 served
Ashwood Grove Edgewater
WI4200485 · 1,046 served
Boyceville Waterworks
WI6170260 · 1,043 served
Balsam Lake Waterworks
WI6490330 · 1,031 served
Crivitz Waterworks
WI4380411 · 1,026 served
Athens Waterworks
WI7370149 · 1,025 served
Shelby Tn of Wedgewood Vly
WI6320311 · 1,020 served
Albany Waterworks
WI1230071 · 1,018 served
Green Lake Waterworks
WI4240217 · 1,002 served
Bristol Village of East
WI2300767 · 1,001 served
Sister Bay Waterworks
WI4150510 · 1,000 served
Belmont Waterworks
WI1330069 · 991 served
Fond Du Lac Tn Water Utility
WI4200429 · 980 served
Benton Waterworks
WI1330070 · 976 served
Valders Waterworks
WI4360437 · 954 served
Blue Mounds Waterworks
WI1130023 · 950 served
Southern Wisconsin Center
WI2520199 · 950 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