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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
201–225 of 1,134Centralia
IL1214220 · 12,182 served
Il American-pontiac
IL1055030 · 11,864 served
Fox Lake
IL0970200 · 11,780 served
River Forest
IL0312610 · 11,717 served
Schiller Park
IL0312850 · 11,709 served
Washington County Water Company
IL1895600 · 11,374 served
Lake of Egypt Pwd
IL1995200 · 11,368 served
Robinson-palestine Water Commission
IL0335030 · 11,331 served
Sugar Grove
IL0890850 · 11,243 served
Burr Ridge
IL0434190 · 11,192 served
Il American-chicago Suburban
IL0315150 · 11,187 served
Columbia
IL1330050 · 11,129 served
Worth
IL0313360 · 10,970 served
Summit
IL0310060 · 10,875 served
Crestwood
IL0310600 · 10,826 served
Highland
IL1190550 · 10,674 served
Wood River
IL1191150 · 10,464 served
Pingree Grove
IL0890160 · 10,365 served
Manhattan
IL1970550 · 10,340 served
Barrington
IL0974080 · 10,327 served
Lyons
IL0311710 · 10,304 served
Peru
IL0990850 · 10,300 served
River Grove
IL0312640 · 10,282 served
Riverdale
IL0312580 · 10,266 served
Murphysboro
IL0770500 · 10,241 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