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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
651–675 of 1,134Winchester
IL1710350 · 1,589 served
Il American-arrowhead
IL0435150 · 1,581 served
Jasper Waterworks Corporation
IL1910020 · 1,578 served
East Dubuque
IL0850100 · 1,565 served
Lcpw - Brooks Farm Subdivision
IL0970280 · 1,563 served
Kincaid
IL0210250 · 1,561 served
Manito
IL1250300 · 1,552 served
Fci-marion
IL1995247 · 1,544 served
Germantown
IL0270350 · 1,537 served
Pheasant Lake Estates Mhp
IL1975385 · 1,528 served
Sandoval
IL1210500 · 1,528 served
Okawville
IL1890400 · 1,521 served
Virginia
IL0170250 · 1,514 served
Greenup
IL0350050 · 1,513 served
Roxana
IL1190900 · 1,509 served
Pleasant Plains
IL1670900 · 1,508 served
Il American-mount Pulaski
IL1070400 · 1,506 served
Lanark
IL0150100 · 1,504 served
Clifton
IL0750250 · 1,500 served
Logan Correctional Center
IL1075520 · 1,500 served
East Hazel Crest
IL0310750 · 1,500 served
Mound Pwd
IL1635050 · 1,500 served
Waterman
IL0370600 · 1,497 served
Prairie Path Water Company-westlake
IL2010070 · 1,493 served
Maple Park
IL0890500 · 1,484 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