Mercer Island, WA property records
As of September 2026, Mercer Island, WA has 7,857 parcels on record, with a median assessed value of $2,226,000 and a median year built of 1969, compiled from King County assessor, treasurer, permit, FEMA, and DNR records aggregated by VetTheHome. As of September 2026, 0 of those 7,857 parcels (0.0%) sit within a FEMA Special Flood Hazard Area, per King County GIS and FEMA flood records aggregated by VetTheHome.
Updated September 2026 · refreshed weekly
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Mercer Island by the numbers
Computed 9/7/2026 from county assessor, treasurer, permit, FEMA, and DNR records.
What the public records show
In the 12 months through September 2026, 195 properties in Mercer Island changed hands at a median recorded sale price of $2,498,000, and 5 building permits were filed, per King County records. As of September 2026, 0 parcels in Mercer Island (0.0%) rely on on-site septic systems rather than municipal sewer, per King County parcel records aggregated by VetTheHome. 178 (2.3%) of parcels in Mercer Island sit in high liquefaction-susceptibility zones mapped by the Washington State DNR. As of September 2026, 108 parcels in Mercer Island carried an unpaid property-tax balance with the King County Treasurer, per records aggregated by VetTheHome. Every figure here is compiled from public records and refreshed weekly; search any Mercer Island address below for parcel-level permit history, tax breakdown, flood and seismic hazards, and septic status.
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