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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
901–925 of 1,134Sharpsburg and Neighboring Area Water Sy
IL0210030 · 868 served
Ilur Liberty Commons Mhp Llc
IL0195400 · 865 served
Hanover
IL0850250 · 863 served
Wee-ma-tuk Water District
IL0570040 · 863 served
East Galesburg
IL0950150 · 860 served
Dahlgren
IL0650150 · 859 served
Brimfield
IL1430150 · 856 served
Aqua Illinois-crystal Clear Water Co.
IL1115150 · 855 served
Prairie Path Water Company-clarendon
IL0435300 · 850 served
Dunfermline-st David Water Commission
IL0575150 · 850 served
Albany
IL1950050 · 846 served
Cissna Park
IL0750200 · 846 served
Annawan
IL0730150 · 843 served
Hardin County Water District No.1
IL0695000 · 843 served
Il American-hardin
IL0130200 · 839 served
South Palmyra Water Commission
IL1170060 · 838 served
Chandlerville
IL0170200 · 838 served
Newman
IL0410250 · 836 served
Alexis
IL1874000 · 836 served
Adams County Water District No 1
IL0015150 · 833 served
Prairie Path Water Company-cherry Hill
IL1975280 · 833 served
Hopedale
IL1790300 · 830 served
Paw Paw
IL1030400 · 830 served
Yates City
IL0950700 · 828 served
Il American-livingston
IL1190600 · 825 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