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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
376–400 of 1,134Eldorado
IL1655030 · 4,715 served
Lebanon
IL1630650 · 4,714 served
Beecher
IL1970050 · 4,713 served
Freeburg
IL1630600 · 4,707 served
Fox River Grove
IL1110200 · 4,702 served
Pittsfield
IL1490750 · 4,697 served
Dupo
IL1630350 · 4,684 served
Calhoun County Rwd
IL0130010 · 4,675 served
Stone Park
IL0313030 · 4,576 served
Athens
IL1290050 · 4,575 served
Auburn
IL1670050 · 4,574 served
Lawrenceville
IL1010150 · 4,524 served
Oglesby
IL0990700 · 4,500 served
Hillsboro
IL1350300 · 4,402 served
Dwight
IL1050250 · 4,400 served
Cortland
IL0370051 · 4,398 served
Sparta
IL1570600 · 4,395 served
Riverton
IL1670950 · 4,279 served
Lakewood
IL1115760 · 4,267 served
Hometown
IL0311320 · 4,240 served
Georgetown
IL1830350 · 4,200 served
Paxton
IL0530250 · 4,200 served
Morrison
IL1950350 · 4,188 served
Aqua Illinois-peotone
IL1970750 · 4,182 served
New Baden
IL0274700 · 4,178 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