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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
876–900 of 1,134Shabbona
IL0370450 · 913 served
Beckemeyer
IL0270200 · 913 served
Shady Oaks Mhp
IL0635225 · 912 served
Grand Valley Village Mhp
IL1670070 · 912 served
Gifford
IL0190250 · 911 served
Mcclure-east Cape Pwd
IL0035050 · 910 served
Spring Lakes Mhp
IL0315145 · 904 served
Sheldon
IL0750800 · 900 served
Bloomington Township Pwd-crestwicke
IL1135120 · 900 served
Willoway Terrace Mhp
IL0317595 · 900 served
Dieterich
IL0490150 · 900 served
Argenta
IL1150050 · 900 served
Bismarck Community Water District
IL1835250 · 900 served
Franklin Grove
IL1030250 · 896 served
Oreana
IL1150450 · 892 served
Galatia
IL1650150 · 887 served
Wyanet
IL0111150 · 886 served
Gateway Mhp
IL1970020 · 884 served
Hanaford
IL0550250 · 883 served
Piper City
IL0530300 · 875 served
Ridgway
IL0590300 · 874 served
Lawrence County Correctional Center
IL1010010 · 870 served
Prairie Path Water Company-holiday Hills
IL1115350 · 868 served
Lakewood Shores Improvement Association
IL1975930 · 868 served
Tallula
IL1290250 · 868 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