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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
601–625 of 1,134Aqua Illinois-mchenry Shores
IL1115020 · 1,862 served
Somonauk
IL0374870 · 1,860 served
Carlyle North Water Company, Inc.
IL0270010 · 1,850 served
Hudson
IL1130700 · 1,847 served
De Pue
IL0110300 · 1,838 served
St Jacob
IL1190950 · 1,835 served
Il American-cairo
IL0035030 · 1,821 served
Carlyle Southwest Pwd
IL0275120 · 1,815 served
Ford Heights
IL0310720 · 1,813 served
Bloomington Township Pwd West Phase
IL1130040 · 1,800 served
Jonesboro
IL1810250 · 1,799 served
Gilman
IL0750450 · 1,793 served
Moweaqua
IL1730200 · 1,785 served
Chenoa
IL1130300 · 1,785 served
Meadowbrook Pwd
IL1195200 · 1,778 served
Zeigler
IL0550750 · 1,774 served
Big Muddy River Cc
IL0810020 · 1,771 served
Grantfork
IL1190350 · 1,766 served
Central Alexander Cnty Pwd
IL0035100 · 1,763 served
Aqua Illinois-rockwell
IL0970110 · 1,762 served
Bunker Hill
IL1170100 · 1,760 served
Orion
IL0730700 · 1,754 served
Roodhouse
IL0610350 · 1,753 served
Delavan
IL1790150 · 1,743 served
Stockton
IL0850450 · 1,728 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