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
101–125 of 493Rice Lake Waterworks
WI6030138 · 9,012 served
Plymouth Utilities
WI4600446 · 8,964 served
Sheboygan Falls Utilities
WI4600455 · 8,687 served
Pewaukee City Water and Sewer Utility
WI2680214 · 8,671 served
Monona Waterworks
WI1130245 · 8,624 served
Delavan Waterworks
WI2650113 · 8,451 served
Rhinelander Water & Wastewater
WI7440126 · 8,234 served
Mukwonago Waterworks
WI2680209 · 8,190 served
Pewaukee Village Waterworks
WI2680229 · 8,166 served
Muskego Water Utility
WI2681741 · 8,150 served
Waupun Utilities
WI1140131 · 8,056 served
Ashland Water Utility
WI8020373 · 8,000 served
Jefferson Waterworks
WI1280104 · 7,926 served
Jackson Waterworks
WI2670111 · 7,844 served
Antigo Waterworks
WI7340086 · 7,780 served
Mt Horeb Waterworks
WI1130247 · 7,756 served
Ripon Water Utility
WI4200476 · 7,716 served
Kimberly Waterworks
WI4450342 · 7,608 served
Ledgeview Tn Sanitary Dist 2
WI4051418 · 7,602 served
New London Waterworks
WI4690398 · 7,187 served
Lake Geneva Utility Commission
WI2650066 · 7,107 served
Kronenwetter Water & Sewer Utility
WI7371700 · 6,931 served
Fox Point Waterworks
WI2410584 · 6,808 served
Village of Lake Hallie Waterworks
WI6090849 · 6,701 served
Town of Brookfield San Dist 4
WI2680239 · 6,419 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
Rice Lake Waterworks
Violation history, PFAS records, and official source links
Plymouth Utilities
Violation history, PFAS records, and official source links
Sheboygan Falls Utilities
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