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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
826–850 of 1,134Lovington
IL1390250 · 1,024 served
Prairie Path Water Company-lake Marian
IL0895200 · 1,022 served
Hoyleton Rwc
IL1895400 · 1,020 served
Hoffman Rural Water Company
IL0275230 · 1,015 served
Alto Pass Water District
IL1815150 · 1,015 served
Il American-country Club
IL0435350 · 1,014 served
Odell
IL1050550 · 1,014 served
Bannockburn
IL0970100 · 1,013 served
Oakbrook Estates Mhp
IL1115125 · 1,012 served
Pleasant Hill
IL1490800 · 1,004 served
Wildwood Estates
IL0995265 · 1,001 served
Camden-littleton Water Commission
IL1695100 · 1,000 served
South Pekin
IL1790650 · 996 served
Alpine Village Mhp
IL0315125 · 994 served
Mazon
IL0630500 · 994 served
Stateville Correctional Center
IL1977910 · 992 served
Milledgeville
IL0150150 · 989 served
Colfax
IL1130350 · 989 served
Newark
IL0930100 · 986 served
Energy
IL1990350 · 984 served
Lockport Heights Sd
IL1977070 · 984 served
Wenona
IL1234950 · 974 served
Raymond
IL1350550 · 974 served
Ridge Farm
IL1830750 · 973 served
Viola
IL1310450 · 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