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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
701–725 of 1,134Nilwood
IL1170750 · 1,394 served
Il American-rosiclare
IL0690160 · 1,387 served
Payson
IL0010550 · 1,386 served
New Berlin
IL1670800 · 1,380 served
Aqua Illinois-philo
IL0190600 · 1,378 served
Astoria
IL0570050 · 1,375 served
Il American-hardin County
IL0690020 · 1,373 served
Tower Lakes
IL0975010 · 1,372 served
Gallatin-white Water District
IL0595100 · 1,370 served
Hebron
IL1110300 · 1,368 served
Gardner
IL0630400 · 1,361 served
Hilltop Mhp
IL1130080 · 1,360 served
Granville
IL1550050 · 1,359 served
Toluca
IL1230250 · 1,348 served
Capron
IL0070100 · 1,343 served
Bonnie Brae Forest Manor Sndst
IL1975140 · 1,338 served
Forreston
IL1410200 · 1,338 served
Ashland
IL0170100 · 1,333 served
Rossville
IL1830800 · 1,331 served
North Utica
IL0990650 · 1,323 served
Warren
IL0850500 · 1,323 served
Harristown
IL1150210 · 1,320 served
East Moreland Wtr Service Assn
IL1975600 · 1,320 served
Barry
IL1490050 · 1,318 served
Otter Lake Water Commission
IL1175200 · 1,318 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.
Illinois Water FAQs
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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