Illinois vs Pennsylvania
Statewide drinking water quality comparison — violation rates, PFAS prevalence, and system-level risk
Quick Answer
Illinois and Pennsylvania have similar open-violation rates (both 0.4%). Illinois has 428 utilities with PFAS records (37.7%) vs. 272 in Pennsylvania (33.5%).
IL · 1,134 utilities
0.4%
Open violation rate
37.7%
PFAS detection rate
0
High/critical risk
99.6%
Safe/low risk
PA · 812 utilities
0.4%
Open violation rate
33.5%
PFAS detection rate
0
High/critical risk
99.9%
Safe/low risk
Head-to-Head Comparison
| Metric | Illinois | Pennsylvania |
|---|---|---|
| Total Utilities | 1,134 | 812 |
| Population Served | 11,973,534 | 11,298,972 |
| Well Water % | 20% on private wells | 30% on private wells |
| Open Violation Rate | 0.4%(5 utilities) | 0.4%(3 utilities) |
| PFAS Detection Rate | 37.7%(428 utilities) | 33.5%(272 utilities) |
| High/Critical Risk Utilities | 0 | 0 |
| Safe/Low Risk Rate | 99.6%(1130 utilities) | 99.9%(811 utilities) |
| Top Contaminants |
State Profiles
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.
Highest-Risk Systems
Pennsylvania
Pennsylvania has 812 community water systems serving approximately 11.3 million residents. Primary water sources include groundwater. The most commonly reported contaminants include disinfection byproducts, lead, nitrates. 30% of Pennsylvania residents rely on private wells. DEP holds primary enforcement authority under the Safe Drinking Water Act.
Key Differences
Open violation rate: Illinois at 0.4% vs. Pennsylvania at 0.4%. Both states have similar open-violation rates.
PFAS detection: Illinois has PFAS records at 37.7% of utilities vs. 33.5% in Pennsylvania. Rates reflect UCMR 5 monitoring (2023–2025).
Well water reliance: Illinois (20% on private wells) vs. Pennsylvania (30% on private wells). Private well users are not regulated under the Safe Drinking Water Act and should test independently.