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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
451–475 of 1,134Abingdon
IL0950050 · 3,275 served
Casey
IL0230050 · 3,274 served
Virden
IL1171100 · 3,274 served
Mount Sterling
IL0090100 · 3,271 served
Indian Head Park
IL0311410 · 3,240 served
Nashville
IL1890300 · 3,230 served
North East Marion County Water Cmpny
IL1210030 · 3,220 served
Knoxville
IL0950300 · 3,120 served
East Dundee
IL0890250 · 3,115 served
Smg Water Coop
IL1370030 · 3,110 served
Sleepy Hollow
IL0890750 · 3,100 served
Momence
IL0910650 · 3,075 served
Christopher
IL0550150 · 3,072 served
Aqua Illinois-hawthorn Woods
IL0975040 · 3,065 served
Lakeside Pwd
IL0775150 · 3,065 served
Savanna
IL0150250 · 3,020 served
Winnebago
IL2010500 · 3,000 served
Oasis Mhp
IL0315185 · 3,000 served
Newton
IL0790100 · 2,977 served
Marquette Heights
IL1790400 · 2,974 served
Dixmoor
IL0310660 · 2,973 served
Bushnell
IL1090150 · 2,972 served
Havana
IL1250200 · 2,963 served
Menard Correctional Center
IL1575550 · 2,950 served
Pittsburg
IL1990600 · 2,948 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