Sammamish
Sammamish, WA water profile — supply sources, drought status, wastewater reuse, and the key water issues facing the city.
sammamish plateau water & sewer
surface water (rivers/reservoirs) · local government · PWSID WA5340900
Below EPA's 15 ppb lead action level at last testing.
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1
Sammamish, WA is a small but growing city, with a population near 52,253 and the 23rd-largest community in Washington. Like much of Washington, Sammamish draws its water primarily from Cascade snowpack, Columbia River, Yakima River, and groundwater.
Sammamish's water outlook is shaped most by drought — the issue that dominates planning across Washington. Snowpack-dependent supplies and the Yakima Basin's irrigation needs drive long-term planning despite a wet reputation.
Sammamish sits in a state that reuses roughly 10% of treated wastewater (developing programs) and currently experiences abnormally dry to moderate drought.
For the bigger picture, see the Washington state water profile and the related issues below.
King County water quality
Source: EPA SDWIS · 2026 Q1
At a glance
- Population ~52,253 (23rd-largest in Washington)
- Primary sources: Cascade snowpack, Columbia River, Yakima River, and groundwater
- Drought: abnormally dry to moderate conditions
- State reuse rate: ~10% of wastewater
Statewide drought history
% of Washington in severe+ drought (Moderate (D1) now).
Source: U.S. Drought Monitor
Common questions
Is tap water safe in Sammamish?
Sammamish's largest water system, SAMMAMISH PLATEAU WATER & SEWER, serves about 79,362 people. EPA records show 0 health-based violation(s) since 2016 and a most-recent 90th-percentile lead level of 1.7 ppb (EPA action level is 15 ppb). Always check your own provider's annual Consumer Confidence Report.
Where does Sammamish get its water?
SAMMAMISH PLATEAU WATER & SEWER draws primarily from surface water (rivers/reservoirs), part of Washington's supply from Cascade snowpack, Columbia River, Yakima River.
Related water issues
Drought
Much of the American West is in a multi-decade dry period that researchers describe as the most severe in over a millennium, reshaping how communities plan for water.
ExploreAgricultural Demand
Agriculture accounts for the majority of consumptive water use in the West, making farm efficiency and water markets central to any supply solution.
ExplorePotable Reuse
Advanced purification turns treated wastewater into water that meets or exceeds drinking-water standards — increasingly essential in water-stressed regions.
ExploreSnowpack Decline
Mountain snow is the West's largest reservoir. As warming shifts snow to rain and melts it earlier, the timing and reliability of water supply are unraveling.
Explore