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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
351–375 of 1,134Flora
IL0250100 · 5,233 served
Il American-fernway
IL0315030 · 5,223 served
Eureka
IL2030200 · 5,216 served
Berkeley
IL0310180 · 5,214 served
Monee
IL1970650 · 5,148 served
Caterpillar Trail Pwd
IL2035030 · 5,125 served
Aqua Illinois-willowbrook
IL1977870 · 5,100 served
Marseilles
IL0990500 · 5,061 served
Brighton
IL1174160 · 5,041 served
South Highway Pwd
IL0775400 · 4,972 served
Murdale Pwd
IL0775200 · 4,963 served
Milan
IL1610400 · 4,945 served
Creve Coeur
IL1790100 · 4,934 served
Olympia Fields
IL0312280 · 4,922 served
Anna
IL1810050 · 4,910 served
Round Lake Park
IL0971600 · 4,900 served
Tuscola
IL0415030 · 4,875 served
Palos Park
IL0311000 · 4,873 served
West Prairie Water Company
IL0410030 · 4,800 served
Breese
IL0270250 · 4,772 served
Prairie Path Water Company-lake Holiday
IL0995200 · 4,750 served
Byron
IL1410100 · 4,743 served
Cherry Valley
IL2010050 · 4,731 served
Sullivan
IL1390300 · 4,729 served
Petersburg
IL1290200 · 4,725 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