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Illinois Water Quality
1,134
Utilities in database
12.0M
Residents served
20%
On private wells
3
Key contaminants tracked
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.
Utilities in Illinois
151–175 of 1,134Troy
IL1191000 · 16,962 served
Marion
IL1990550 · 16,855 served
North Chicago
IL0971250 · 16,813 served
Canton
IL0570250 · 16,748 served
Country Club Hills
IL0310540 · 16,500 served
Bridgeview
IL0310270 · 16,467 served
Chatham
IL1670300 · 16,423 served
Westchester
IL0313150 · 16,241 served
La Grange
IL0311530 · 16,200 served
Mount Vernon
IL0810300 · 15,793 served
Palos Heights
IL0312370 · 15,500 served
Norridge
IL0312040 · 15,251 served
Cahokia Heights
IL1635000 · 15,250 served
Bethalto
IL1190150 · 15,210 served
Il American-lincoln
IL1075030 · 15,200 served
Dixon
IL1030200 · 15,096 served
Macomb
IL1090350 · 15,051 served
Wildwood Subdivision - Lake Co Pw
IL0977350 · 14,832 served
Midlothian
IL0311920 · 14,819 served
Washington
IL1790750 · 14,793 served
Il American-sterling
IL1955040 · 14,782 served
Morris
IL0630600 · 14,775 served
Hickory Hills
IL0311200 · 14,505 served
Lindenhurst
IL0971000 · 14,500 served
Forest Park
IL0310900 · 14,340 served
Key Contaminant Concerns in Illinois
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.
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always from human activity — nitrate interferes with the blood's ability to carry oxygen. The United States produces over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination.
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.
Illinois Water FAQs
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Data source: Utility data from EPA SDWIS. 1,134 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-17