Water in Washington.
Seattle and Tacoma draw pristine Cascade snowmelt — among the highest-quality U.S. municipal source water. PFAS contamination from Joint Base Lewis-McChord affects multiple Pierce County systems. Hanford Site groundwater plumes are a generational issue.
How Washington regulates drinking water.
Among the stricter states. Washington State Action Levels for five PFAS compounds (2022). Active Hanford radioactive-groundwater remediation.
Washington State Department of Health — Office of Drinking Water
Washington's water history, in order.
The contamination events, regulatory shifts, and major settlements that define how this state thinks about drinking water today.
- 1989
Hanford Federal Facility Agreement initiates massive radioactive-groundwater cleanup.
- 2017
PFAS contamination identified at Joint Base Lewis-McChord.
- 2022
Washington adopts State Action Levels for five PFAS compounds.
The actual water you drink.
The physical rivers, aquifers, lakes, and reservoirs that feed Washington's public water systems. Source quality is the foundation of tap quality — and where the long-term protection fights happen.
- riverCedar River + Tolt River Watersheds
Seattle pristine Cascade snowmelt.
- riverGreen River
Tacoma.
- aquiferSpokane Valley-Rathdrum Prairie Aquifer
Spokane region.
- riverColumbia River
Tri-Cities (near Hanford).
Source-water mix
~70% surface water (Cascade snowmelt), ~30% groundwater
Major cities served
Seattle · Spokane · Tacoma · Vancouver · Bellevue
Who actually serves the water.
The largest public water systems in Washington by population served. Click your ZIP after to see the full live EWG report for your specific utility.
- Seattle Public UtilitiesSeattle metro1,500Kserved
- Tacoma WaterTacoma320Kserved
- City of Spokane Water DepartmentSpokane220Kserved
Where the contamination comes from.
Every state has a different industrial fingerprint. The industries below are the dominant historical and active contamination sources in Washington's drinking water systems.
Hanford Site radioactive groundwater plumes — among the largest U.S. environmental remediation sites. Joint Base Lewis-McChord PFAS contamination affects Pierce County. Boeing manufacturing legacy chlorinated solvents.
What state data flags most consistently.
Drawn from EPA SDWIS sampling records, EWG state summaries, and regional regulatory action over the past five years. Read the full deep dive on each.
Lead
A neurotoxic metal that leaches from old pipes and solder. No safe level for children.
PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
Trihalomethanes (TTHMs)
Byproducts of chlorinating water. Linked to bladder cancer at chronic exposure.
Arsenic
A naturally occurring carcinogen. Highest in private wells and the rural Southwest.
Risk isn't evenly distributed.
Pierce County residents near Joint Base Lewis-McChord face the most-documented PFAS exposure. Tri-Cities residents face Hanford legacy contamination.
~17% on private wells, mostly rural eastern WA.
What's coming for Washington's water.
Wildfire burn-scar runoff threatens Cedar / Tolt watersheds. Snowpack decline affects Cascades-fed systems. Coastal saltwater intrusion in shallow Puget Sound wells.
Statewide mandate
Washington 2018 lead-in-schools rule requires testing in all schools and licensed childcare. Results published.
Five questions for your next Consumer Confidence Report.
Your utility is required to send you a Consumer Confidence Report annually. Most are dense and procedural. These are the questions worth following up on for Washington specifically.
- 1
If I'm in Pierce County, is my system in the Joint Base Lewis-McChord PFAS zone?
- 2
If I'm in Tri-Cities, has my Columbia River system been impacted by Hanford plumes?
- 3
Has my school posted current lead testing results?
Most state regulators allow public records requests for the underlying lab reports behind your CCR — your utility should be able to provide them on request.
What's changed in Washington water law.
Drinking water regulation moves at the state level as much as the federal level. Below are notable recent bills and regulatory actions specific to Washington.
- 2022
WA State Action Levels for five PFAS compounds.
- 2021
Healthy Environment for All Act — water-quality equity requirements.
For PFAS: NSF/ANSI P473 or RO. For Hanford-area concerns: certified reverse osmosis.
We don't recommend brands — the NSF/ANSI certification number matters more than the name on the box.
This is the state. Your address is the answer.
State-level patterns don't tell you about your specific tap. Run your ZIP for the live EWG contaminant report on your utility — or build a personalized Water File for your household.
Source-water mix, utility counts, lead-service-line estimates, and private-well shares are approximate, drawn from EPA SDWIS public data and state primacy-agency summaries. Contaminant rankings reflect EWG state-level monitoring data and regional regulatory action — they are not exhaustive. Timeline events are publicly documented. See methodology for the full sourcing. Search EPA SDWIS for Washington