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Illinois Water Quality
1,134
Utilities in database
12.0M
Residents served
5
With open violations
472
PFAS monitored
Quick Answer
Illinois public drinking water is served by 1,134 EPA-tracked water systems, providing service to approximately 12.0 million residents through public utilities. 5 of those systems currently have open health-based violations on record in the EPA federal database. 472 systems have official PFAS monitoring records from the EPA UCMR 5 program (2023–2025). About 20% of IL residents use private wells, which fall outside federal utility compliance monitoring.
5 Illinois water systems have open health-based violations 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 Illinois
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 Illinois
Illinois has 1,134 community water systems serving approximately 12.0 million residents. Primary water sources include groundwater. The most commonly reported contaminants include lead, disinfection byproducts, nitrates. 20% of Illinois residents rely on private wells. IEPA holds primary enforcement authority under the Safe Drinking Water Act.
Highest Risk Utilities
Illinois systems with open health-based violations in EPA records.
Safest Large Utilities
Illinois systems with no open health violations serving 10,000+ residents.
Utilities in Illinois
776–800 of 1,134Danvers
IL1130450 · 1,183 served
Valier
IL0550600 · 1,182 served
Walnut Hill
IL1210600 · 1,180 served
Minier
IL1790450 · 1,180 served
South Barrington
IL0310200 · 1,175 served
Divernon
IL1670450 · 1,172 served
Mechanicsburg-buffalo Water Commission
IL1675150 · 1,170 served
Kingston
IL0370250 · 1,160 served
Atwood
IL0414060 · 1,155 served
Malta
IL0370350 · 1,143 served
Gorham
IL0770350 · 1,143 served
Prospect Water District
IL1655110 · 1,140 served
Mounds
IL1530150 · 1,135 served
Prairie Path Water Company-ferson Creek
IL0895800 · 1,134 served
Oquawka
IL0710300 · 1,125 served
Johnsburg No.2
IL1115080 · 1,124 served
Royalton
IL0555030 · 1,118 served
Flanagan
IL1050400 · 1,110 served
Oraville Water District
IL0775250 · 1,108 served
Il American-valley Marina
IL0935100 · 1,102 served
Greenfield
IL0610150 · 1,097 served
Griggsville
IL1490300 · 1,097 served
Worden
IL1191200 · 1,096 served
Heartville Pwd
IL0495200 · 1,092 served
Crossville
IL1930150 · 1,091 served
Key Contaminant Concerns in Illinois
These contaminants appear most frequently in Illinois 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)
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always caused by human activity — nitrate is converted in the digestive system to nitrite, which then reacts with hemoglobin to form methemoglobin, a form of hemoglobin that cannot carry oxygen. In the body, nitrite also reacts with amines in food to form N-nitroso compounds (nitrosamines) — known carcinogens classified by the IARC as Group 2A (probable human carcinogens). The United States applies over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination in U.S. groundwater.
EPA limit: 10 mg/L
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)
City Water Reports in Illinois
Tap water quality pages for Illinois cities — violations, PFAS records, utility profiles, and official source links.
Independent Water Testing
Find a certified lab in Illinois
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. Illinois labs can test for PFAS, lead, nitrates, bacteria, and dozens of other contaminants.
Explore Water Quality in Illinois
Danvers
Violation history, PFAS records, and official source links
Valier
Violation history, PFAS records, and official source links
Walnut Hill
Violation history, PFAS records, and official source links
PFAS monitoring records — Illinois
472 water systems in Illinois with EPA UCMR 5 records
Active drinking water violations
5 open health-based violations on record — view official EPA SDWIS data
Lead in Illinois drinking water
State-specific lead data, violation utilities, and testing guidance
PFAS in Illinois drinking water
State-specific PFAS data, MCL context, and treatment options
Certified water testing labs in Illinois
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 Illinois Drinking Water
Does Illinois drinking water have PFAS?
472 Illinois water systems have EPA UCMR 5 PFAS monitoring records (2023–2025)
Which Illinois water utilities have open violations?
5 systems have open health-based violations in EPA SDWIS — search for your utility
How do I test my water in Illinois?
State-certified labs for PFAS (EPA 533/537.1), lead, nitrate, and bacteria testing
What treatment removes PFAS from IL tap water?
Reverse osmosis removes PFAS, lead, arsenic, and nitrates — cost, maintenance, and NSF certification explained
What do Illinois PFAS records tell me about my water?
EPA limits, health context, and what UCMR 5 detection above MRL means for your water
How is Illinois water quality data sourced here?
EPA SDWIS violations, UCMR 5 PFAS records, and CCR data — sources, accuracy notes, and limitations
Illinois 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: 2026-04-17