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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
76–100 of 1,134Montgomery
IL0894690 · 28,956 served
Glen Ellyn
IL0430450 · 28,850 served
Lake in the Hills
IL1110400 · 28,661 served
Huntley
IL1110350 · 28,495 served
New Lenox
IL1970700 · 27,690 served
Il American-granite City
IL1195030 · 27,549 served
Oak Forest
IL0312190 · 27,478 served
Round Lake Beach
IL0971550 · 27,200 served
Wilmette
IL0313300 · 27,087 served
Edwardsville
IL1190250 · 26,808 served
Chicago Heights
IL0310450 · 26,184 served
Batavia
IL0894130 · 26,098 served
Woodstock
IL1110950 · 25,630 served
Belvidere
IL0070050 · 25,339 served
Morton Grove
IL0311950 · 25,297 served
West Chicago
IL0430900 · 25,166 served
Elmwood Park
IL0310780 · 25,000 served
Harvey
IL0311110 · 25,000 served
Il American-homer Township
IL1970100 · 24,543 served
Zion
IL0972000 · 24,442 served
Lisle
IL0430551 · 24,233 served
Melrose Park
IL0311860 · 24,206 served
Westmont
IL0430950 · 24,161 served
Maywood
IL0311830 · 24,090 served
Frankfort
IL1970400 · 24,000 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