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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
1,001–1,025 of 1,134Buckhorn Ranch Estates Mhp
IL0310070 · 702 served
South Wilmington
IL0630650 · 700 served
Prairie Path Water-bahl Water Company
IL0855200 · 700 served
Vandalia Correctional Center
IL0515500 · 700 served
Pocahontas
IL0050200 · 697 served
Scottville Rural Water Company, Inc.
IL1170010 · 695 served
Fairmount
IL1830250 · 690 served
Tampico
IL1950550 · 689 served
Potomac
IL1830650 · 685 served
White Heath Waterworks
IL1475050 · 685 served
Creal Springs
IL1990300 · 683 served
Il American-terra Cotta
IL1110080 · 681 served
Shadow Wood Mhp
IL0195320 · 680 served
Saybrook
IL1130950 · 679 served
Il American-lombard Heights
IL0435700 · 679 served
Westfield
IL0230200 · 678 served
River Oaks Estates Mhp
IL0310395 · 677 served
Bradford
IL1750050 · 676 served
Arenzville Rural Water Cooperative
IL0170080 · 675 served
Lake County Pw- Hawthorn Woods
IL0970450 · 675 served
West City
IL0550650 · 664 served
Dalzell
IL0110250 · 663 served
Cedarville
IL1770050 · 663 served
Evansville
IL1570250 · 660 served
Cambridge Courts Mhp
IL0971540 · 658 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