The Environmental Working Group's Tap Water Database has analyzed water quality data from more than 48,000 utilities serving 280 million Americans. Their findings reveal that hundreds of contaminants are present in U.S. drinking water — many at levels that exceed health guidelines, even when they meet legal standards.
| Contaminant | Exposure | Health Risk | EWG Finding |
|---|---|---|---|
| PFAS (Forever Chemicals) | 2,858 systems | Cancer, immune disruption, developmental harm | No safe level established |
| Lead | 186M Americans | Brain damage, developmental harm in children | No safe level — causes harm at any dose |
| Chromium-6 | 250M Americans | Carcinogen linked to stomach cancer | Legal limit 500× higher than safe level |
| Nitrates | Widespread | Infant illness, thyroid disruption, colorectal cancer | Legal limit may be too high |
| Arsenic | 77M Americans | Bladder, lung, and skin cancers | Legal limit 50× higher than cancer risk level |
| Chloroform (THMs) | Most U.S. systems | Cancer, reproductive harm | Byproduct of chlorine disinfection |
| Atrazine (Herbicide) | 30M Americans | Endocrine disruption, reproductive harm | Detected in 90% of U.S. water samples |