We read 11 results from King County Water District No 90’s 2025 water quality report. No results over a legal limit; 2 above a health goal or guideline.
Serves about 20,100 people · Water system ID WA5341150 · Read the district’s 2025 report (opens in a new tab)
Open this district in the water lookupCompare with your own test results, see the district map and get matched filters.
Results from the 2025 report
Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.
| Contaminant | Result | Health goal | Legal limit | What it means |
|---|---|---|---|---|
| Arsenicaverage · range 0.3 to 0.6 · Cedar River supply (Seattle) · 2025 report, page 2 | 0.5 ppb | 0.004 ppb | 10 ppb | Above the health goal125x the health goal |
| Lead90th percentile of 31 homes tested, 0 over the action level · Customer taps · 2025 report, page 2 | 1.16 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal5.8x the health goal |
| Bariumaverage · range 0.0013 to 0.0022 · printed as 1.7 ppb · Cedar River supply (Seattle) · 2025 report, page 2 | 0.0017 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorineaverage · range 0.18 to 1.64 · Cedar River supply (Seattle), highest of 2 sources · 2025 report, page 2 | 0.91 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of 31 homes tested, 0 over the action level · Customer taps · 2025 report, page 2 | 0.05 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)average · range 19 to 33 · KCWD 90 wellfield · 2025 report, page 2 | 25 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)average · range 21 to 32 · KCWD 90 wellfield · 2025 report, page 2 | 25 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.61 to 0.77 · KCWD 90 wellfield, highest of 2 sources · 2025 report, page 2 | 0.72 ppm | 1 ppm | 4 ppm | Below the health goal |
| Manganeseaverage · range 0.001 to 0.04 · KCWD 90 wellfield · 2025 report, page 2 | 0.02 ppm | — | 0.05 ppm guideline | Within the guideline |
| Turbidity (cloudiness)average · range 0.17 to 3.65 · Cedar River supply (Seattle) · 2025 report, page 2 | 0.36 NTU | None set | 1 NTU | Below the legal limit |
| Total organic carbonaverage · range 0.4 to 1.1 · Cedar River supply (Seattle) · 2025 report, page 2 | 0.7 ppm | None set | None | No health limit |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper.
What you can do
Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.
Lead
Found: Lead
What removes it: Certified carbon block or RO.
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