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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
101–125 of 1,134Freeport
IL1770200 · 23,930 served
South Elgin
IL0890800 · 23,648 served
Loves Park
IL2010150 · 23,335 served
Rolling Meadows
IL0312730 · 23,329 served
Lockport
IL1970500 · 23,100 served
Yorkville
IL0930250 · 23,000 served
Great Lakes Naval Training Station
IL0975227 · 23,000 served
Roselle
IL0434820 · 22,897 served
Mchenry
IL1110600 · 22,335 served
East Peoria
IL1790200 · 22,284 served
Villa Park
IL0430800 · 22,263 served
Carbondale
IL0770150 · 22,107 served
Bloomingdale
IL0430100 · 22,018 served
South Holland
IL0312970 · 22,000 served
Darien
IL0430270 · 21,751 served
Park Forest
IL0314740 · 21,687 served
Blue Island
IL0310240 · 21,494 served
East Moline
IL1610250 · 21,374 served
Grayslake
IL0970250 · 21,248 served
Geneva
IL0890350 · 21,247 served
Crest Hill
IL1970250 · 21,169 served
Dolton
IL0310690 · 20,510 served
Libertyville
IL0970900 · 20,500 served
Evergreen Park
IL0310840 · 19,943 served
Jacksonville
IL1370200 · 19,903 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