State Hub
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
201–225 of 493New Holstein Waterworks
WI4080270 · 3,012 served
Park Falls Waterworks
WI8510130 · 2,993 served
Amery Waterworks
WI6490328 · 2,962 served
Lake Delton Waterworks
WI1570664 · 2,914 served
Oconto Falls Waterworks
WI4430496 · 2,892 served
Kewaunee Waterworks
WI4310281 · 2,848 served
Mendota Mental Health Inst
WI1130235 · 2,787 served
Rome Water Utility
WI7010108 · 2,775 served
Genoa City Waterworks
WI2650058 · 2,766 served
Luxemburg Waterworks
WI4310282 · 2,737 served
Belleville Waterworks
WI1130209 · 2,712 served
Lomira Waterworks
WI1140151 · 2,701 served
Brockway Sanitary Dist 1
WI6270299 · 2,692 served
Denmark Waterworks
WI4050351 · 2,684 served
Osceola Waterworks
WI6490341 · 2,680 served
Mondovi Waterworks
WI6060193 · 2,667 served
Spooner Waterworks
WI8660305 · 2,653 served
Juneau Waterworks
WI1140058 · 2,627 served
Williams Bay Waterworks
WI2650060 · 2,601 served
Hayward Water Utility
WI8580532 · 2,552 served
New Lisbon Waterworks
WI7290132 · 2,526 served
Poynette Waterworks
WI1110037 · 2,520 served
Deerfield Waterworks
WI1130223 · 2,510 served
Fennimore Waterworks
WI1220096 · 2,507 served
Winneconne Waterworks
WI4710354 · 2,502 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