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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
51–75 of 493Menomonie Waterworks
WI6170268 · 15,950 served
Oconomowoc Waterworks
WI2680227 · 15,805 served
Hartford Waterworks
WI2670110 · 15,805 served
Menasha Elec & Water Util
WI4710334 · 15,144 served
Waunakee Waterworks
WI1130265 · 14,879 served
Greendale Waterworks
WI2410571 · 14,393 served
Whitefish Bay Waterworks
WI2410597 · 14,272 served
Verona Waterworks
WI1130259 · 14,030 served
Whitewater Waterworks
WI2650056 · 14,000 served
Allouez Waterworks
WI4050455 · 13,923 served
Shorewood Waterworks
WI2410607 · 13,535 served
Plover Waterworks
WI7500726 · 13,486 served
Chippewa Falls Waterworks
WI6090456 · 13,375 served
Stoughton Waterworks
WI1130078 · 13,078 served
Darboy Sanitary Dist 1
WI4450117 · 13,024 served
Glendale Waterworks
WI2410168 · 12,883 served
Port Washington Waterworks
WI2460054 · 12,853 served
Brown Deer Waterworks
WI2410556 · 12,741 served
Baraboo Waterworks
WI1570085 · 12,703 served
Fort Atkinson Waterworks
WI1280103 · 12,390 served
Grafton Waterworks
WI2460111 · 12,269 served
Platteville Waterworks
WI1220115 · 12,268 served
Little Chute Waterworks
WI4450338 · 12,168 served
Cedarburg L & W Commission
WI2460108 · 11,800 served
Sussex Village Hall & Water Utility
WI2680233 · 11,750 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