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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
1,051–1,075 of 1,134Keyesport
IL0274580 · 625 served
Beach Mhp
IL0970010 · 624 served
Golden
IL0010250 · 620 served
Lenzburg
IL1630700 · 616 served
Hutsonville
IL0330100 · 613 served
New Boston
IL1310250 · 613 served
Cowden
IL1730050 · 612 served
Liberty
IL0010350 · 609 served
Prairie Path Water Company-coventry Hill
IL2015150 · 608 served
Palmyra
IL1170800 · 605 served
Raleigh Water District
IL1655120 · 605 served
Patoka
IL1210400 · 603 served
Damiansville
IL0275200 · 602 served
Bedford Park
IL0310120 · 602 served
Baldwin
IL1570050 · 601 served
Union-york Water District
IL0235400 · 600 served
Buckley
IL0750150 · 600 served
Stanford
IL1131000 · 600 served
Prairie Path Water Company-northern Hill
IL1775050 · 600 served
Silver Glen Homeowner's Association
IL0890040 · 595 served
Union
IL1110900 · 594 served
West Shore Park Subdivision
IL0977370 · 590 served
Davis
IL1770150 · 589 served
Fairview
IL0570450 · 588 served
St Francisville
IL1010250 · 583 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