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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
501–525 of 1,134Sesser
IL0550450 · 2,556 served
Aviston
IL0270100 · 2,545 served
Odin
IL1210350 · 2,543 served
Greenwood-creek Nation Water Company
IL0555200 · 2,530 served
Kenilworth
IL0311500 · 2,514 served
Carrollton
IL0610050 · 2,513 served
Carthage
IL0670250 · 2,510 served
Diamond
IL0630250 · 2,508 served
Colona East
IL0730400 · 2,501 served
Amboy
IL1030050 · 2,500 served
Pinckneyville Correctional Center
IL1450010 · 2,470 served
Clayton-camp Point Water Commission
IL0015200 · 2,470 served
Il American-villa Grove
IL0410350 · 2,467 served
Park City Mhp
IL0975575 · 2,460 served
Galva
IL0730450 · 2,449 served
Il American-farmington
IL0570500 · 2,448 served
Lewistown
IL0570600 · 2,400 served
Central Stickney Sd
IL0315570 · 2,400 served
West Prairie Water Co-op
IL1090030 · 2,395 served
Ewing-ina Water Commission
IL0555350 · 2,393 served
Ellery Water Corp
IL0470010 · 2,380 served
Catlin
IL1830150 · 2,380 served
Dawson
IL1670400 · 2,375 served
Poplar Grove
IL0070150 · 2,372 served
Nokomis
IL1350450 · 2,370 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