State Hub
Wisconsin Water Quality
493
Utilities in database
4.1M
Residents served
1
With open violations
189
PFAS monitored
Quick Answer
Wisconsin public drinking water is served by 493 EPA-tracked water systems, providing service to approximately 4.1 million residents through public utilities. 1 of those systems currently have open health-based violations on record in the EPA federal database. 189 systems have official PFAS monitoring records from the EPA UCMR 5 program (2023–2025). About 38% of WI residents use private wells, which fall outside federal utility compliance monitoring.
1 Wisconsin water system has an open health-based violation recorded in EPA SDWIS. An open violation means a contaminant exceeded a federal limit and the violation has not been formally resolved in the federal database. Check individual utility pages for current status.
Open Health-Based Violations in Wisconsin
Records sourced from EPA SDWIS. A record may be under review or resolved at the utility level but not yet updated in federal records. Water Utility Report does not determine whether water is safe to drink.
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.
Highest Risk Utilities
Wisconsin systems with open health-based violations in EPA records.
Safest Large Utilities
Wisconsin systems with no open health violations serving 10,000+ residents.
Utilities in Wisconsin
26–50 of 493Stevens Point Waterworks
WI7500141 · 26,717 served
Superior Water Light & Power Company
WI8160147 · 26,084 served
De Pere Waterworks Sa 1
WI4050453 · 25,660 served
Fitchburg Utility Dist 1
WI1130231 · 24,500 served
Watertown Waterworks
WI1280044 · 23,945 served
Middleton Waterworks
WI1130242 · 23,868 served
Menomonee Falls Ww - Surface Water
WI2680082 · 23,867 served
Franklin Water Utility
WI2410563 · 22,500 served
Village of Caledonia Water Utility
WI2520184 · 21,819 served
Grand Chute Tn San Dist 1
WI4450429 · 21,583 served
South Milwaukee Waterworks
WI2410144 · 21,340 served
Howard Waterworks
WI4050468 · 21,133 served
Germantown Water Utility
WI2670105 · 20,027 served
Wis Rapids Water Works & Lighting Comm
WI7720108 · 20,000 served
Marshfield Utilities
WI7720165 · 18,815 served
Cudahy Waterworks
WI2410169 · 18,659 served
Hudson Waterworks
WI6560087 · 18,558 served
Onalaska Waterworks
WI6320327 · 18,000 served
Fox Crossing Utilities West
WI4710358 · 18,000 served
Ashwaubenon Waterworks
WI4050456 · 17,730 served
Kaukauna Utilities
WI4450336 · 17,493 served
Bellevue Waterworks
WI4050459 · 16,715 served
Beaver Dam Water Utility
WI1140059 · 16,200 served
Weston Municipal Utilities
WI7370163 · 16,000 served
River Falls Waterworks
WI6480246 · 16,000 served
Key Contaminant Concerns in Wisconsin
These contaminants appear most frequently in Wisconsin utility records or pose elevated risk in this region based on EPA data.
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. Critically, a utility's water quality report can show zero detected lead at the treatment plant while your specific tap still delivers elevated lead — because the contamination happens inside the distribution system and your home's plumbing, not at the source.
EPA limit: 15 ppb (action level)
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.
EPA limit: 80 µg/L (TTHMs) / 60 µg/L (HAA5)
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.
EPA limit: 10 ppb
City Water Reports in Wisconsin
Tap water quality pages for Wisconsin cities — violations, PFAS records, utility profiles, and official source links.
Independent Water Testing
Find a certified lab in Wisconsin
Utility compliance records show what water systems report to the EPA. An independent test from a certified laboratory confirms what's actually in your tap water. Wisconsin labs can test for PFAS, lead, nitrates, bacteria, and dozens of other contaminants.
Explore Water Quality in Wisconsin
Stevens Point Waterworks
Violation history, PFAS records, and official source links
Superior Water Light & Power Company
Violation history, PFAS records, and official source links
De Pere Waterworks Sa 1
Violation history, PFAS records, and official source links
PFAS monitoring records — Wisconsin
189 water systems in Wisconsin with EPA UCMR 5 records
Active drinking water violations
1 open health-based violation on record — view official EPA SDWIS data
Lead in Wisconsin drinking water
State-specific lead data, violation utilities, and testing guidance
PFAS in Wisconsin drinking water
State-specific PFAS data, MCL context, and treatment options
Certified water testing labs in Wisconsin
Labs certified for PFAS (EPA 533/537.1), lead, and bacteria testing
Water treatment options
Reverse osmosis, activated carbon, and filtration guides with cost ranges
Data sources and methodology
How WaterUtilityReport.com sources and validates official EPA data
Common Questions About Wisconsin Drinking Water
Does Wisconsin drinking water have PFAS?
189 Wisconsin water systems have EPA UCMR 5 PFAS monitoring records (2023–2025)
Which Wisconsin water utilities have open violations?
1 systems have open health-based violations in EPA SDWIS — search for your utility
How do I test my water in Wisconsin?
State-certified labs for PFAS (EPA 533/537.1), lead, nitrate, and bacteria testing
What treatment removes PFAS from WI tap water?
Reverse osmosis removes PFAS, lead, arsenic, and nitrates — cost, maintenance, and NSF certification explained
What do Wisconsin PFAS records tell me about my water?
EPA limits, health context, and what UCMR 5 detection above MRL means for your water
How is Wisconsin water quality data sourced here?
EPA SDWIS violations, UCMR 5 PFAS records, and CCR data — sources, accuracy notes, and limitations
Wisconsin Water FAQs
Data sources: Utility compliance and violation data from EPA SDWIS (Safe Drinking Water Information System). PFAS monitoring records from EPA UCMR 5 (Unregulated Contaminant Monitoring Rule 5, 2023–2025). Contaminant data from EPA and ATSDR public references. This page summarizes public records — it is not a compliance determination. Methodology →
Last updated: 2026-04-19