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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
176–200 of 493Black River Falls Waterworks
WI6270244 · 3,608 served
Seymour Waterworks
WI4450337 · 3,601 served
Waterloo Waterworks
WI1280115 · 3,520 served
Sauk City Waterworks
WI1570105 · 3,518 served
Stanley Waterworks
WI6090462 · 3,500 served
Barron Light & Water Dept
WI6030125 · 3,423 served
Peshtigo Waterworks
WI4380442 · 3,420 served
Mosinee Waterworks
WI7370159 · 3,406 served
Somerset Waterworks
WI6560137 · 3,334 served
Johnson Creek Waterworks
WI1280107 · 3,318 served
Ellsworth Waterworks
WI6480239 · 3,304 served
Brillion Waterworks
WI4080221 · 3,262 served
Freedom Sanitary District
WI4451607 · 3,260 served
Boscobel Waterworks
WI1220089 · 3,237 served
Wisconsin Dells Waterworks
WI1110113 · 3,232 served
Algoma Waterworks
WI4310280 · 3,219 served
Brodhead Waterworks
WI1230072 · 3,216 served
Rothschild Waterworks
WI7370161 · 3,190 served
Ladysmith Waterworks
WI8550131 · 3,184 served
Tomahawk Waterworks
WI7350127 · 3,180 served
Lodi Waterworks
WI1110100 · 3,146 served
Sherwood Waterworks
WI4080271 · 3,114 served
Oostburg Waterworks
WI4600445 · 3,110 served
Lake Como Sanitary Dist 1
WI2651536 · 3,038 served
Hortonville Water Utility
WI4450411 · 3,028 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