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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
476–493 of 493Avoca Waterworks
WI1250074 · 545 served
Warrens Waterworks
WI6420305 · 540 served
Boyd Waterworks
WI6090449 · 540 served
Ettrick Waterworks
WI6620273 · 536 served
Gresham Waterworks
WI4590454 · 534 served
Merrillan Waterworks
WI6270294 · 531 served
Spacious Acres Mobile Home Community
WI1280114 · 525 served
Melrose Waterworks
WI6270293 · 524 served
Clark County Rehabilitation & Living Center
WI6100336 · 510 served
Adell Waterworks
WI4600435 · 510 served
Withee Waterworks
WI6100283 · 506 served
St Joseph San Dist 1
WI6320318 · 503 served
Lake Drive Water Trust
WI2683440 · 500 served
Three Lakes Sanitary District
WI7440129 · 500 served
Country Estates Sanitary District Town of Lyons 1
WI2650127 · 500 served
Interlaken Resort and Village
WI2650143 · 500 served
Waldo Waterworks
WI4600456 · 500 served
Drummond Sanitary District
WI8040129 · 500 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