Pressure washing costs in Seattle

Seattle checks a building's birth year before it gets washed. The city's July 2026 stormwater manual says apartment, condo and other multi-unit buildings built or renovated from 1950 through 1980 are the likeliest to have PCBs in exterior paint, caulk and sealants. Unless lab tests show none, wash water from those buildings can't go into a storm drain, the street or a neighbor's yard. It has to be collected and disposed of under a King County discharge permit.

A detached house is exempt from that testing, and so is its garage or shed. If you own a condo in a 1960s or '70s building, though, the PCB question belongs to the whole building before anyone washes its walls.

For everyone else, the manual sets two conditions. A routine wash-down of a building may run to the public drainage system only when no detergent is used and water is kept to a minimum. Sidewalks get the same pass, but only after they've been swept. Depending on where you live in the city, an outdoor drain may lead to the combined sewer, to the drainage system, or straight into local waters.

Soap changes the job. Seattle Public Utilities tells cleaning businesses that once detergent, soap or bleach goes into the water, it must be collected or sent to the sanitary sewer. For a mossy roof, SPU adds that moss killer shouldn't go on in the rain, because it's highly toxic to fish.