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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
626–650 of 1,134Cambria
IL1990100 · 1,727 served
Crainville
IL1990250 · 1,711 served
Pierron
IL1194760 · 1,709 served
Maroa
IL1150300 · 1,700 served
Atlanta
IL1070050 · 1,692 served
St Rose Pwd
IL0275250 · 1,688 served
Port Byron
IL1610550 · 1,678 served
Sheridan Correctional Center
IL0995840 · 1,670 served
Pontiac Correctional Center
IL1055500 · 1,665 served
Bement
IL1470050 · 1,661 served
Eaton Pwd
IL0335100 · 1,655 served
Neoga
IL0350150 · 1,636 served
Pekin Fed Correctional Inst and Prsncmp
IL1790030 · 1,635 served
Vienna
IL0870350 · 1,618 served
Shawnee Correctional Center
IL0870010 · 1,617 served
Grayville
IL1934460 · 1,613 served
Earlville
IL0990150 · 1,613 served
Benld
IL1170050 · 1,612 served
Dunlap
IL1430250 · 1,603 served
Prairie Path Water Company-oakwood
IL1830600 · 1,600 served
Erie
IL1950200 · 1,600 served
Jerome
IL1670600 · 1,600 served
Herscher
IL0910450 · 1,600 served
Western Il Correctional Center
IL0090010 · 1,600 served
Teutopolis
IL0490450 · 1,599 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