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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
976–1,000 of 1,134Keithsburg
IL1310150 · 747 served
Ingalls Park Subdivision
IL1975880 · 744 served
Tiskilwa
IL0111050 · 740 served
New Windsor
IL1310500 · 740 served
Brownstown
IL0510100 · 740 served
Tilden
IL1570700 · 740 served
Oakland
IL0290300 · 739 served
Shawnee Valley Pwd
IL1815550 · 738 served
Vermont
IL0570950 · 738 served
Clover Leaf Village Mhp
IL1610160 · 732 served
Brookport
IL1270050 · 730 served
Aqua Illinois-eastwood Manor
IL1115250 · 728 served
Taylor Springs
IL1350650 · 724 served
Ashkum
IL0750050 · 724 served
Moro Pwd
IL1195250 · 723 served
Thayer
IL1671250 · 721 served
Enchanted Village
IL1195160 · 720 served
Cooks Mills Water Association
IL0295200 · 720 served
Kirkwood
IL1870050 · 714 served
Greenview Estates Mhp
IL0070060 · 710 served
Clayton
IL0010100 · 709 served
Kansas
IL0450200 · 707 served
Il American-alpine Heights
IL1970030 · 707 served
Tonica
IL0991150 · 705 served
Lost Lake Utility District
IL1415100 · 704 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