Tap Water Quality Report
Tap water quality in Seattle, Washington
Tap water in Seattle, Washington receives a grade of D (68/100) from TapWaterSafety.org. It's served by 2 public water systems, primarily City of Seattle Water Department. The most significant water quality concerns are: Lead detected in source water; Haloacetic Acids (HAA5) significantly above health guideline; Chromium-6 detected; Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database, and Seattle's published Consumer Confidence Report.
What's in Seattle's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utilities serving Seattle.
Lead detected in source water
Severe concernLead detected at 1.1 ppb. EWG considers no level of lead safe; EPA's action level is 15 ppb.
Haloacetic Acids (HAA5) significantly above health guideline
Moderate concernHaloacetic Acids (HAA5) detected at 25.5 ppb, 255x above the EWG health guideline of 0.1 ppb.
Chromium-6 detected
Moderate concernChromium-6 detected at 0.46 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 27.3 ppb, 455x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 28.9 ppb, 289x above the EWG health guideline of 0.1 ppb.
Water systems serving Seattle
Seattle is served by 2 public water systems. Click any utility to see its complete grade card and treatment plant contact info.
City of Seattle Water Department
- Lead detected in source water
- Haloacetic Acids (HAA5) significantly above health guideline
- Chromium-6 detected
SEATTLE PUBLIC UTILITIES
- Haloacetic acids (HAA9) significantly above health guideline
- Haloacetic acids (HAA5) significantly above health guideline
- Total trihalomethanes (TTHMs) significantly above health guideline
Recommended filters for Seattle
Filters matched to the specific contaminants in Seattle's water supply.
NSF/ANSI 53 certified for lead removal
$80-$750NSF 53 is the gold standard certification for lead removal. Required when lead is a documented concern.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Reverse Osmosis
$249-$750Chromium-6 requires reverse osmosis for reliable removal. Standard carbon filters do not address it.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in Seattle's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
27.3 ppb | 0.06 | — | — | — | — | — | 455× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
28.9 ppb | 0.1 | 60.0 | 60 | — | — | — | 289× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
25.5 ppb | 0.1 | 60 | 60 | — | — | 2022 | 255× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
28.7 ppb | 0.15 | 80.0 | 100 | — | — | — | 192× over |
| Trichloroacetic acid Disinfection byproduct |
14.9 ppb | 0.1 | — | — | — | — | — | 149× over |
| Chloroform Disinfection byproduct |
27.0 ppb | 0.4 | — | — | — | — | — | 68× over |
| Dichloroacetic acid Disinfection byproduct |
12.7 ppb | 0.2 | — | — | — | — | — | 64× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
20.0 ppb | 0.6 | 80 | 100 | — | — | 2022 | 33× over |
| Bromodichloromethane Disinfection byproduct |
1.69 ppb | 0.06 | — | — | — | — | — | 28× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.488 ppb | 0.02 | — | — | — | 0.02 | 2023 | 24× over |
| Radium, combined (-226 and -228) Radiological |
0.71 pCi/L | 0.05 | 5.0 | — | — | — | — | 14× over |
| Nitrate Inorganic |
0.837 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2023 | 6.0× over |
| Chromium (hexavalent) Heavy metal |
0.116 ppb | 0.02 | — | — | — | — | — | 5.8× over |
| Bromate Disinfection byproduct |
0.352 ppb | 0.1 | 10.0 | 10 | 10 | 0.1 | — | 3.5× over |
| Bromochloroacetic acid Disinfection byproduct |
0.0664 ppb | 0.02 | — | — | — | — | — | 3.3× over |
| Chlorate Disinfection byproduct |
16.1 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
1.26 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Vanadium Other |
0.483 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
1.93 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Strontium Radiological |
0.0291 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Lead Heavy metal |
1.41 ppb | 0 | 15 | 5 | 10 | 0.2 | 2022 | — |
| Contaminant | Detected (2023) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Chromium-6 (Hexavalent) Heavy metal |
0.488 ppb | 0.02 | — | — | — | 0.02 | 24× over |
| Nitrate Inorganic |
0.837 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 6.0× over |
| Contaminant | Detected (2022) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) Disinfection byproduct |
25.5 ppb | 0.1 | 60 | 60 | — | — | 255× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
20.0 ppb | 0.6 | 80 | 100 | — | — | 33× over |
| Lead Heavy metal |
1.41 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from City of Seattle Water Department.
General Contact
Water Quality Contact
For questions about contaminants or test results.
Treatment Plant
ZIP codes served
Seattle's public water systems serve the following ZIP codes: