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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
1,026–1,050 of 1,134Chapin
IL1370050 · 658 served
Hoyleton
IL1890200 · 658 served
Tamms
IL0030100 · 653 served
Equality
IL0590050 · 652 served
Matherville
IL1310200 · 651 served
Forest View Mhp
IL2010030 · 650 served
Crescent City
IL0750300 · 650 served
Aqua Illinois-ivanhoe
IL0970180 · 650 served
Ej Water-niantic
IL1150400 · 648 served
Vergennes
IL0770550 · 648 served
Coffeen
IL1350150 · 647 served
Deer Creek
IL1794320 · 647 served
Bayles Lake Lot Owners Association
IL0755110 · 645 served
Oneida
IL0950400 · 644 served
Cordova
IL1610150 · 640 served
Green Valley
IL1790250 · 638 served
Ashmore
IL0290050 · 637 served
Bartelso
IL0270150 · 635 served
Cisne
IL1910050 · 634 served
Golconda
IL1510100 · 630 served
Channahon East
IL1970070 · 630 served
St Libory
IL1631200 · 628 served
Creston
IL1410150 · 627 served
Alpha
IL0730050 · 626 served
Ursa
IL0010700 · 626 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.
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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