Drinking-water safety · Lead (90th-percentile)
Big Cities With the Highest Lead Levels
Large city water systems with the highest most-recent 90th-percentile lead result.
Dayton leads "Big Cities With the Highest Lead Levels" at 470 ppb.
| # | City | Lead (90th-percentile) |
|---|---|---|
| 1 | Dayton 141,407 served | 470 ppb |
| 2 | Elgin 114,797 served | 53 ppb |
| 3 | Boston 675,647 served | 22.5 ppb |
| 4 | Aurora 183,000 served | 20.6 ppb |
| 5 | Rockford 147,051 served | 14 ppb |
| 6 | Omaha 660,000 served | 12.3 ppb |
| 7 | Modesto 218,771 served | 12 ppb |
| 8 | Olathe 143,014 served | 11 ppb |
| 9 | Chicago 2,746,388 served | 8.8 ppb |
| 10 | Quincy 106,000 served | 8.7 ppb |
| 11 | Cambridge 118,214 served | 8 ppb |
| 12 | Canton 107,113 served | 8 ppb |
| 13 | Detroit 633,218 served | 7.5 ppb |
| 14 | Yonkers 211,569 served | 7.1 ppb |
| 15 | Naperville 156,406 served | 7.1 ppb |
Method: Limited to systems serving 100,000+ people with a reported lead sample. EPA action level is 15 ppb.
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1 refresh; violations since 2016