Is Seattle, WA Tap Water Safe to Drink?
Graded F — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
42.3/100
waterverge.com Seattle, WA — Water Quality Report
Seattle's drinking water received a grade of F (42.3 out of 100), indicating failing water quality. The city's 14 water systems serve approximately 1,161,339 residents using surface water.
Lead levels were measured at 2.0 ppb (90th percentile), well within EPA limits. PFAS testing under UCMR 5 found no detectable forever chemicals.
The system has 1889 violations on record, including 138 health-based violations. 120 remain unresolved.
What to know about Seattle's water
Seattle ranks #273 out of 294 cities in Washington for water quality, placing it among the lowest-rated in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
Hexavalent chromium (chromium-6) was detected at 0.20 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.
As a major metropolitan system serving over 1.2M residents, Seattle faces large-scale infrastructure challenges including aging pipes and the complexity of treating water across a vast distribution network.
The system has seen 270 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Seattle, WA water safe to drink?
Seattle's drinking water has significant quality concerns based on EPA testing data. With a grade of F (42.3/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 14 water systems serve approximately 1,161,339 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Seattle
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Seattle's water quality assessment. Grade: F (42.3/100).
2 health-based. Contaminants: Revised Total Coliform Rule, E. COLI, Nitrate.
Federal disaster declaration (FEMA DR-3629). Flood event — may have impacted local water infrastructure.
1 health-based. Contaminants: Nitrate.
3 health-based. Contaminants: Public Notice, Fluoride, Arsenic.
Federal disaster declaration (FEMA DR-4539). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Seattle's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Seattle's water system has 1,889 total violations on record, including 138 health-based violations. 120 remain unresolved. 270 violations were issued in the last 5 years.
Flood & environmental risk
King County has experienced 10 federally declared disasters since 1990. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Green River, Duwamish River, Duwamish R, Cedar River.
Where does Seattle's water come from?
Seattle's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 14 water systems serving approximately 1,161,339 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Green River (river), Duwamish River (river), Duwamish R (river), Cedar River (river).
What Seattle residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Seattle's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Seattle's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Seattle
Industrial polluters nearby
Reported releases to surface water by facilities near Seattle, ranked by pounds discharged annually.
Total reported releases to surface water: 16 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
NUCOR STEEL SEATTLE INC SEATTLE, WA98106 | Zinc compounds | 11 | 3.6 mi |
ACE GALVANIZING INC SEATTLE, WA98108 | Zinc compounds | 5 | 7.1 mi |
ASH GROVE CEMENT CO. SEATTLE, WA98134 | Zinc compounds | 0 | 3.5 mi |
GLACIER NORTHWEST INC EAST MARGINAL WAY PLANT SEATTLE, WA98134 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 0 | 5.0 mi |
SHELL SEATTLE DISTRIBUTION TERMINAL SEATTLE, WA98134 | Lead compounds | 0 | 2.4 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Seattle
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- LOCKHEED WEST SEATTLE2.5 mi
- PACIFIC SOUND RESOURCES2.7 mi
- HARBOR ISLAND LEAD2.8 mi
- WYCKOFF CO EAGLE HARBOR7.7 mi
- LOWER DUWAMISH WATERWAY8.0 mi
+ 2 more sites
Source: EPA Superfund National Priorities List
Flood & disaster history
King County has experienced 10 federally declared disasters since 1990. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Seattle's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 2.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 610.00 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | ND | HI | µg/L | PFAS | Not Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Seattle compares by contaminant
Explore where Seattle ranks among all Washington cities for specific contaminants.
Water source & infrastructure
Where Seattle's water comes from
Seattle's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 1,161,339 people through 14 water systems.
Water bodies near Seattle
Seattle is located near 4 notable water bodies. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Seattle
| System Name | PWSID | Population | Source |
|---|---|---|---|
| SEATTLE PUBLIC UTILITIES | WA5377050 | 1,091,904 | SW |
| KING COUNTY WATER DISTRICT #20 | WA5338950 | 38,974 | SWP |
| KING COUNTY WATER DISTRICT #125 | WA5341998 | 17,546 | SWP |
| SKYWAY WATER & SEWER | WA5338800 | 12,036 | SWP |
| Ravenwing Ranch | WA53AB782 | 250 | GW |
| VALLEY MOBILE HOME PARK | OH4503112 | 120 | GW |
| CHERRYWOOD MOBILE HOME MANOR | WA5312630 | 120 | GW |
| COUNTRY HOMES MOBILE PARK | ID2290007 | 90 | GW |
| HIDDEN VILLAGE MHP, LLC | ID2290004 | 66 | GW |
| GOLF MHP | OR4100588 | 60 | GW |
| HOT SPRINGS COURT | 083090312 | 55 | GW |
| BRUNSWICK HILLS MHP | OH5200012 | 50 | GW |
| RIVER VILLAGE MHP | OR4105854 | 40 | GW |
| Majestic Oaks Water System | WA5355860 | 28 | GW |
How Seattle compares
Full Washington rankings →Seattle's score of 42.3/100 is below the average of 53/100 among major Washington cities. It outscores 4 of 10 nearby cities. 6 of 10 nearby cities score higher.
Nearby cities
View Washington rankings →Compare Seattle water quality
Head-to-head reports vs other large US cities — grades, lead, PFAS, and Superfund / TRI proximity.
- Seattle vs Charlotte, NC
- Seattle vs Herndon, VA
- Seattle vs Orlando, FL
- Seattle vs Smithtown (T), NY
- Seattle vs Smithtown (T), NY
ZIP codes served by Seattle
The water systems serving Seattle cover 1 ZIP code. Select any ZIP to see which water systems serve that area.
About Seattle, WA
Wikipedia →Seattle is the most populous city in the U.S. state of Washington and the Pacific Northwest region of North America. It is the 18th-most populous city in the United States with a population of 780,995 in 2024, while the Seattle metropolitan area at over 4.15 million residents is the 15th-most populous metropolitan area in the nation. The city is the county seat of King County, the most populous county in Washington. Seattle's growth rate of 21.1% between 2010 and 2020 made it one of the country's fastest-growing large cities.
Learn more about your water
Guides and resources related to Seattle's water quality findings.
Explore water quality across King
Frequently asked questions
Is Seattle, WA tap water safe to drink?
Seattle's water quality earned a grade of F (42.3/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #273 out of 294 cities tested in Washington.
What contaminants are in Seattle's water?
Lead was measured at 2.0 ppb (90th percentile). No PFAS compounds were detected. 1889 violations are on record.
How is Seattle's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Seattle?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Seattle's water come from?
Seattle's water is sourced from Surface water. The city has 14 water systems serving approximately 1,161,339 residents.
What health violations has Seattle's water system had?
Seattle has 138 health-based violations on record. The most recent violation was recorded in December 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 120 violations remain unresolved.
How does Seattle's water compare to other cities?
Seattle ranks #273 out of 294 cities in Washington (better than 7% of state cities) and #14816 out of 15744 cities nationally (6th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.