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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
176–200 of 1,134Antioch
IL0970050 · 14,175 served
Chicago Ridge
IL0310480 · 14,130 served
Wauconda
IL0971850 · 14,084 served
Wood Dale
IL0431200 · 14,012 served
Caseyville
IL1630250 · 13,798 served
Lincolnwood
IL0311650 · 13,463 served
Channahon
IL1970200 · 13,380 served
Western Springs
IL0313180 · 13,274 served
Hazel Crest
IL0311170 · 13,098 served
La Grange Park
IL0311560 · 13,011 served
U of I-champaign
IL0195500 · 13,000 served
Rantoul
IL0190650 · 13,000 served
Northlake
IL0314710 · 12,840 served
Taylorville
IL0210600 · 12,806 served
Minooka
IL0630550 · 12,800 served
Jersey Rwc
IL0835300 · 12,750 served
Herrin
IL1990400 · 12,747 served
Glen Carbon
IL1190300 · 12,618 served
Plano
IL0930200 · 12,600 served
Kewanee
IL0730650 · 12,509 served
Richton Park
IL0312550 · 12,504 served
Markham
IL0311770 · 12,500 served
Winnetka
IL0313330 · 12,475 served
Warrenville
IL0430833 · 12,350 served
Effingham
IL0490250 · 12,252 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