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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
801–825 of 1,134Hamel
IL1190450 · 1,087 served
Robinson Correctional Center
IL0330010 · 1,085 served
Irvington
IL1890250 · 1,081 served
Meredosia
IL1370300 · 1,075 served
Edinburg
IL0210150 · 1,068 served
Elkville
IL0770300 · 1,068 served
Morrisonville
IL0210300 · 1,068 served
Goreville
IL0870200 · 1,068 served
Thomasboro
IL0190950 · 1,066 served
Highway 37 North Pwd
IL1995100 · 1,065 served
Enfield
IL1930200 · 1,064 served
Prairie Path Water Company-harbor Ridge
IL0975620 · 1,064 served
Shawneetown
IL0590350 · 1,054 served
Ava
IL0770050 · 1,053 served
Coulterville
IL1570150 · 1,052 served
Suburban Apartments (de Kalb Univ Dvl)
IL0375148 · 1,050 served
Chebanse
IL0754240 · 1,044 served
Dixon Correctional Center
IL1035500 · 1,038 served
Illiopolis
IL1670550 · 1,037 served
Marine
IL1190700 · 1,037 served
Lincoln Correctional Center
IL1075450 · 1,036 served
Washburn
IL2034940 · 1,032 served
Wamac
IL1214920 · 1,030 served
Buncombe Water District
IL0775420 · 1,030 served
Ej Water-sangchris
IL1670230 · 1,025 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