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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
551–575 of 1,134Thomson Maximum Security Center
IL0150030 · 2,166 served
Norris City
IL1930350 · 2,155 served
Graham Correctional Site
IL1355100 · 2,155 served
Carbon Cliff
IL1610100 · 2,134 served
Tremont
IL1790700 · 2,114 served
Prophetstown
IL1950400 · 2,100 served
Richmond
IL1110750 · 2,089 served
Cambridge
IL0730300 · 2,086 served
Carrier Mills
IL1650050 · 2,085 served
Ej Water-mcwc
IL1350020 · 2,075 served
Elmwood
IL1430300 · 2,058 served
Farmer City
IL0390150 · 2,055 served
Henderson Pwd
IL1350010 · 2,045 served
Il American-fisher
IL0190150 · 2,026 served
Limestone-walters Pwd
IL1430020 · 2,023 served
Clay County Water Inc
IL0250020 · 2,015 served
Rockdale
IL1970850 · 2,012 served
Hinckley
IL0370200 · 2,006 served
Southeast Joliet Sd
IL1977490 · 2,000 served
Roanoke
IL2030550 · 2,000 served
Kirkland
IL0370300 · 2,000 served
Phoenix
IL0312490 · 1,994 served
Clinton County East Pwd
IL0275150 · 1,980 served
Dix-kell Water Commssion
IL0815100 · 1,972 served
New Athens
IL1631050 · 1,970 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