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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
251–275 of 1,134Il American-jerseyville
IL0830250 · 8,737 served
Beach Park
IL0970190 · 8,710 served
Clarendon Hills
IL0430250 · 8,702 served
West Frankfort
IL0550700 · 8,650 served
Rock Falls
IL1950450 · 8,620 served
Harrisburg
IL1650200 · 8,524 served
Calumet Park
IL0310420 · 8,442 served
Chester
IL1570100 · 8,407 served
Gilberts
IL0890400 · 8,366 served
Greenville
IL0050050 · 8,310 served
North Tazewell Pwd
IL1795780 · 8,300 served
Prairie Path Water Co-whispering Hills
IL1115700 · 8,300 served
Crete
IL1970300 · 8,275 served
Hillside
IL0311230 · 8,200 served
Benton
IL0550050 · 8,104 served
Island Lake
IL0974540 · 8,066 served
Mill Creek Water Reclamation District
IL0890120 · 8,000 served
Western Illinois University
IL1095510 · 8,000 served
Fosterburg Pwd
IL1195220 · 7,940 served
Lincolnshire
IL0970950 · 7,940 served
Salem
IL1210450 · 7,905 served
Il American-south Beloit
IL2010450 · 7,893 served
Long Creek Township Pws
IL1155150 · 7,850 served
Broadview
IL0310300 · 7,847 served
West Dundee
IL0890950 · 7,845 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