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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
1,101–1,125 of 1,134Xenia
IL0250300 · 542 served
Shipman
IL1170950 · 541 served
Farina
IL0510150 · 540 served
Lyndon
IL1950300 · 537 served
Good Hope
IL1090250 · 536 served
Wilsonville
IL1171200 · 536 served
Burlington
IL0890150 · 535 served
Mound City
IL1530100 · 526 served
Chadwick
IL0150050 · 523 served
Belknap
IL0870050 · 516 served
Grand Ridge
IL0990200 · 515 served
Wapella
IL0390250 · 513 served
Tovey
IL0210650 · 512 served
Reynolds
IL1614800 · 508 served
South Bluff Mhp
IL2010460 · 507 served
Colp
IL1990200 · 506 served
Franciscan Sisters of Chicago
IL0310110 · 505 served
Shoreline Trc Mhp
IL0975615 · 504 served
Bookwalter Woods Mhp
IL0635125 · 504 served
Mississippi Manufactured Home Community
IL1610350 · 503 served
Vienna Correctional Center
IL0875510 · 501 served
Decatur Mhp, Llc
IL1150160 · 500 served
Rankin
IL1830700 · 500 served
London Mills
IL0574620 · 500 served
Lake Barrington
IL0971080 · 500 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