Tap water · WA
Seattle Public Utilities
EPA system ID WA5377050 · serves about 1,161,961 people. Every US utility must publish an annual water quality report — here’s the official one (2025), and below it, our plain-English translation.
Read the official report →What Seattle Public Utilities found in 2025
11 detected analytes from the utility’s own annual report, hand-normalized — nothing was near or over a federal health-based limit.
| Detected | Level | Limit | % of limit | Status |
|---|---|---|---|---|
| Haloacetic Acids | 28 ppb | 60 ppb | 47% | Within limit |
| Total Trihalomethanes | 34 ppb | 80 ppb | 43% | Within limit |
| Chlorine | 1 ppm | 4 ppm | 25% | Within limit |
| Fluoride | 0.7 ppm | 4 ppm | 18% | Within limit |
| Coliform, Total | 0.6 % | 5 % | 12% | Within limit |
| Lead (90th percentile) | 1.6 ppb | 15 ppb | 11% | Within limit |
| Copper (90th percentile) | 0.12 ppm | 1.3 ppm | 9% | Within limit |
| Arsenic | 0.5 ppb | 10 ppb | 5% | Within limit |
| Barium | 1.7 ppb | 2,000 ppb | 0% | Within limit |
| Total Organic Carbon | 1.3 ppm | — | — | No federal limit |
| Turbidity (highest) | 0.36 NTU | — | — | No federal limit |
Levels and limits are as printed in the utility’s report (“limit” is the EPA MCL, action level, residual limit, or secondary guideline that applies to that row; “ND” = not detected). Utilities publish these reports annually — we re-check every covered utility each July, after the federal publication deadline. Detected doesn’t mean dangerous — most detections sit far below their limits. This is education, not medical advice.
Zip codes covered
98101 · 98102 · 98103 · 98104 · 98105 · 98106 · 98107 · 98108 · 98109 · 98112 · 98115 · 98116 · 98117 · 98118 · 98119 · 98121 · 98122 · 98125 · 98126 · 98133 · 98134 · 98136 · 98144 · 98177 · 98199
Boundary zips partially served by other systems are deliberately unlisted — check your exact zip.