County · Illinois
Cook County, Illinois: drinking water records
This overview covers 167 ZIP codes and 156 community water systems in Cook County. It also stands in for 0 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| Cicero IL0310510 | 83,000 | 120 | 0 | 1 | 5 ppb |
| Wheeling IL0314970 | 39,725 | 120 | 0 | 1 | 1.3 ppb |
| Calumet City IL0310390 | 37,000 | 240 | 2 | 2 | 12.4 ppb |
| Maywood IL0311830 | 24,090 | 120 | 0 | 1 | 5.4 ppb |
| South Holland IL0312970 | 22,000 | 240 | 1 | 2 | 7.9 ppb |
| Park Forest IL0314740 | 21,687 | 60 | 0 | 1 | 2.3 ppb |
| Bellwood IL0310150 | 19,156 | 120 | 0 | 1 | 9.1 ppb |
| Lemont IL0311620 | 17,500 | 240 | 0 | 1 | 20 ppb |
| Western Springs IL0313180 | 13,274 | 60 | 0 | 1 | 2.0 ppb |
| Richton Park IL0312550 | 12,504 | 180 | 0 | 2 | 7.4 ppb |
| Chicago IL0316000 | 2,721,308 | 240 | 0 | 0 | 7 ppb |
| Schaumburg IL0314890 | 75,750 | 120 | 0 | 0 | 1.4 ppb |
| Evanston IL0310810 | 74,486 | 120 | 0 | 0 | 8 ppb |
| Arlington Heights IL0314030 | 73,320 | 120 | 0 | 0 | 8.8 ppb |
| Palatine IL0312340 | 70,875 | 120 | 0 | 0 | 7.5 ppb |
| Skokie IL0312880 | 66,422 | 120 | 0 | 0 | 8.0 ppb |
| Des Plaines IL0310630 | 60,675 | 240 | 0 | 0 | 11.1 ppb |
| Oak Lawn IL0312220 | 58,362 | 120 | 0 | 0 | 8.1 ppb |
| Orland Park IL0312310 | 58,020 | 120 | 0 | 0 | 0 ppb |
| Berwyn IL0310210 | 57,250 | 60 | 0 | 0 | 1.8 ppb |
| Tinley Park IL0314910 | 56,703 | 120 | 0 | 0 | 0 ppb |
| Oak Park IL0312250 | 54,583 | 120 | 0 | 0 | 5.1 ppb |
| Hoffman Estates IL0311290 | 50,179 | 120 | 0 | 0 | 1.4 ppb |
| Glenview IL0311020 | 47,856 | 120 | 0 | 0 | 9.8 ppb |
| Buffalo Grove IL0314180 | 43,212 | 120 | 0 | 0 | 0 ppb |
ZIP reports in Cook County
No ZIP report in this county is published yet.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.