Water Quality Report · Updated October 07, 2026
City of Seattle Water Department
City of Seattle Water Department delivers tap water graded B (77/100) by TapWaterSafety.org. The utility serves approximately 753,000 residents in Seattle, Washington using surface water from the Cedar/Tolt watersheds. The most significant water quality concerns are: Lead detected in source water; Haloacetic Acids (HAA5) significantly above health guideline; Chromium-6 detected. For questions, the utility can be reached at (206) 332-9402.
Is Seattle tap water safe to drink?
City of Seattle Water Department delivers tap water that earns a grade of B (77/100) from TapWaterSafety.org — a good rating, with only minor concerns relative to health-based guidelines.
The utility serves 753,000 residents in Seattle, drawing from surface water (Cedar/Tolt watersheds) and disinfecting with free chlorine.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Haloacetic Acids (HAA5), Haloacetic Acids (HAA5), Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs), Total Trihalomethanes (TTHMs), Total Trihalomethanes (TTHMs), Chromium-6 (Hexavalent), Chromium-6 (Hexavalent), Chromium-6 (Hexavalent), Nitrate, Nitrate, Nitrate, Lead, Lead, Lead. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for City of Seattle Water Department.
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.
Contact City of Seattle Water Department
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Water Quality Contact
For questions about contaminants, test results, or your Consumer Confidence Report.
Treatment Plant
Recommended water filters for Seattle
Filters matched to the specific contaminants in this water supply.
Filter certified for lead (NSF/ANSI 53 or 58)
$180-$750When lead is a concern, use a filter certified for lead reduction under NSF/ANSI 53 or 58.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Reverse osmosis certified for chromium (NSF/ANSI 58)
$429-$599Chromium-6 needs reverse osmosis for reliable reduction. 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.
Score breakdown
This utility's overall score of 77/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 (HAA5) Disinfection byproduct |
25.5 ppb | 0.1 | 60 | 60 | — | — | 2022 | 255× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
24.0 ppb | 0.1 | 60 | 60 | — | — | 2023 | 240× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
20.9 ppb | 0.1 | 60 | 60 | — | — | 2024 | 209× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
20.0 ppb | 0.6 | 80 | 100 | — | — | 2022 | 33× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
18.2 ppb | 0.6 | 80 | 100 | — | — | 2024 | 30× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
16.6 ppb | 0.6 | 80 | 100 | — | — | 2023 | 28× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.488 ppb | 0.02 | — | — | — | 0.02 | 2023 | 24× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.46 ppb | 0.02 | — | — | — | 0.02 | 2024 | 23× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.419 ppb | 0.02 | — | — | — | 0.02 | 2022 | 21× over |
| Nitrate Inorganic |
0.837 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2023 | 6.0× over |
| Nitrate Inorganic |
0.8 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2024 | 5.7× over |
| Nitrate Inorganic |
0.662 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2022 | 4.7× over |
| Lead Heavy metal |
1.1 ppb | 0 | 15 | 5 | 10 | 0.2 | 2024 | — |
| Lead Heavy metal |
1.25 ppb | 0 | 15 | 5 | 10 | 0.2 | 2023 | — |
| Lead Heavy metal |
1.41 ppb | 0 | 15 | 5 | 10 | 0.2 | 2022 | — |
| Contaminant | Detected (2024) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
18.2 ppb | 0.6 | 80 | 100 | — | — | 30× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
20.9 ppb | 0.1 | 60 | 60 | — | — | 209× over |
| Lead Heavy metal |
1.1 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| Chromium-6 (Hexavalent) Heavy metal |
0.46 ppb | 0.02 | — | — | — | 0.02 | 23× over |
| Nitrate Inorganic |
0.8 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 5.7× over |
| Contaminant | Detected (2023) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
16.6 ppb | 0.6 | 80 | 100 | — | — | 28× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
24.0 ppb | 0.1 | 60 | 60 | — | — | 240× over |
| Lead Heavy metal |
1.25 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| 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 |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
20.0 ppb | 0.6 | 80 | 100 | — | — | 33× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
25.5 ppb | 0.1 | 60 | 60 | — | — | 255× over |
| Lead Heavy metal |
1.41 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| Chromium-6 (Hexavalent) Heavy metal |
0.419 ppb | 0.02 | — | — | — | 0.02 | 21× over |
| Nitrate Inorganic |
0.662 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 4.7× over |
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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database, and City of Seattle Water Department's Consumer Confidence Report.
City of Seattle Water Department service area
This water system serves 1 community in King County, Washington. Click any city for its dedicated tap water quality page.
Find the right filter for Seattle water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.