Cook County tap water
0 of 108 water systems serving Cook County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 161 community water systems list this county as served; 106 serve 3,300+ people with full PFAS testing.
- 14 had a health-based violation since 2021-10-26.
Largest systems serving this county
| System | Source | People served (whole system) | PFAS above a 2024 level? | Violations since 2021-10-26 |
|---|---|---|---|---|
| Chicago | Surface water | 2,721,308 | No | 0 |
| Cicero | Purchased surface water | 83,000 | No | 1 |
| Schaumburg | Purchased surface water | 75,750 | No | 0 |
| Evanston | Surface water | 74,486 | No | 0 |
| Arlington Heights | Purchased surface water | 73,320 | No | 0 |
| Palatine | Purchased surface water | 70,875 | No | 0 |
| Skokie | Purchased surface water | 66,422 | No | 0 |
| Des Plaines | Purchased surface water | 60,675 | No | 0 |
| Oak Lawn | Purchased surface water | 58,362 | No | 0 |
| Orland Park | Purchased surface water | 58,020 | No | 0 |
| Tinley Park | Purchased surface water | 56,703 | No | 0 |
| Oak Park | Purchased surface water | 54,583 | No | 0 |
Which one is yours? A county usually has several utilities. Your bill or your utility's annual water-quality report names yours. Population is for the whole system, which can cross county lines.
Not medical or legal advice. UCMR 5 results are screening data, not compliance determinations.
Sources and freshness
Public-water-system facts, violations and lead/copper results: EPA ECHO SDWA download (SDWIS snapshot 2026-10-13). PFAS and lithium results: EPA UCMR 5 final data (sampling 2023–2025). Both are U.S. government works, downloaded 2026-10-26. Numbers are computed by the published method; the same fields are in the open data files.