Drinking water quality · 2024
· Verified
What's in Seattle, WA tap water
Every one of the 10 core regulated contaminants reported for Seattle, WA came in below its federal limit.
- !10 of 27 core regulated contaminants reported — 17 never appear in this report
- ✓Nothing over a federal limit
- ✓No open federal violations
+How this score is calculated
Every system starts at 100. Points come off for measured levels, for the federal violation record, and for how much of the core regulated set the utility actually reported. All three inputs are the utility's own published numbers and EPA's own records.
- −0 contaminants at or above a federal limit
- −0 contaminants within 20% of a limit
- −0 open health-based violations
- −0 open monitoring / reporting violations
- −0 health-based violations resolved in the last 5 years
- −14 core regulated contaminants never reported (10/27)
A 90–100 · B 80–89 · C 70–79 · D 60–69 · F below 60. A system reporting under a third of the core set is capped at C however clean its numbers look — a short report is not a clean bill of health.
Full grading methodology, constant for constant →+12 contaminants were measured and came in below the limitShow all
| Contaminant | Measured | Federal limit |
|---|---|---|
| HAA5 | 33 ug/L | 60 ug/L |
| TTHM | 43 ug/L | 80 ug/L |
| Chlorine | 1 mg/L | 4 mg/L |
| Lead | 2.8 ug/L | 15 ug/L |
| Fluoride | 0.7 mg/L | 4 mg/L |
| Copper | 0.12 mg/L | 1.3 mg/L |
| Turbidity | 0.04 NTU | 1 NTU |
| Bromate | 0.3 ug/L | 10 ug/L |
| Arsenic | 0.23 ug/L | 10 ug/L |
| Nitrate | 0.08 mg/L | 10 mg/L |
| Barium | 1.2 ug/L | 2000 ug/L |
| TOC | 1.24 mg/L | — |
What this report doesn't tell you
17 of the 27 contaminants a community water system normally reports do not appear anywhere in Seattle, WA's data. Absent is not the same as absent-from-the-water — it means nobody published a number.