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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
301–325 of 493Independence Waterworks
WI6620276 · 1,500 served
Black Earth Waterworks
WI1130211 · 1,493 served
Edgar Waterworks
WI7370150 · 1,491 served
Orfordville Waterworks
WI1540132 · 1,475 served
Bonduel Waterworks
WI4590450 · 1,475 served
Phillips Waterworks
WI8510131 · 1,473 served
Grantsburg Waterworks
WI8070310 · 1,460 served
Muscoda Waterworks
WI1220112 · 1,453 served
Augusta Waterworks
WI6180231 · 1,450 served
Mishicot Waterworks
WI4360430 · 1,432 served
West Baraboo Waterworks
WI1570112 · 1,414 served
Spring Valley Waterworks
WI6480249 · 1,409 served
Cornell Waterworks
WI6090458 · 1,390 served
Woodville Waterworks
WI6560138 · 1,386 served
Markesan Waterworks
WI4240218 · 1,365 served
Cadott Waterworks
WI6090450 · 1,352 served
Maple Bluff Waterworks
WI1130234 · 1,342 served
Black Creek Waterworks
WI4450408 · 1,336 served
Elroy Waterworks
WI7290122 · 1,333 served
Montello Waterworks
WI4390281 · 1,329 served
Hillsboro Waterworks
WI6630257 · 1,325 served
Loyal Waterworks
WI6100329 · 1,308 served
Manawa Waterworks
WI4690345 · 1,300 served
Marion Waterworks
WI4690396 · 1,293 served
Blair Waterworks
WI6620274 · 1,280 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