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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
301–325 of 1,134Illinois State University-normal
IL1135510 · 6,600 served
La Grange Highlands Sanitary District
IL0315860 · 6,600 served
Carlinville
IL1170150 · 6,598 served
Mahomet
IL0190450 · 6,580 served
Winthrop Harbor
IL0971950 · 6,565 served
Elburn
IL0890300 · 6,559 served
Geneseo
IL0730500 · 6,539 served
Northern Illinois University-dekalb
IL0375500 · 6,500 served
Carterville
IL1990150 · 6,484 served
Aqua Illinois-candlewick Dvn
IL0075050 · 6,426 served
Countryside
IL0310570 · 6,420 served
Dallas Rural Water District
IL0710010 · 6,370 served
Metropolis
IL1270150 · 6,309 served
Carmi
IL1930100 · 6,307 served
Fort Massac Pwd
IL1275050 · 6,290 served
Fairfield
IL1910100 · 6,202 served
Williamsville
IL1671300 · 6,198 served
Braidwood
IL1970150 · 6,194 served
Chillicothe
IL1430200 · 5,996 served
Beardstown
IL0170150 · 5,951 served
Peoria Heights
IL1434750 · 5,908 served
Mount Zion
IL1150350 · 5,833 served
Pinckneyville
IL1450150 · 5,804 served
Hoopeston
IL1830450 · 5,802 served
Pana
IL0210500 · 5,800 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