As of July 25, 2021, except for occupant limits on group living arrangements regulated under state law or on short-term rentals as defined in RCW 64.37.010, and any lawful limits on occupant load per square foot or generally applicable health and safety provisions as established by applicable building code or city ordinance, a city or town may not regulate or limit the number of unrelated persons that may occupy a household or dwelling unit.This law applies to Washington State Counties, Municipalities, and Cities. RCW 36.01.227, RCW 35A.21.314, RCW 35.21.682.
This basically means that if you’re landlord in Washington State, you cannot limit the number of people that can reside in one house, unless your city or town specifically has regulations that are based on square footage of the rental, and the city or town can prove there is a valid health or safety concern to have that regulation in place.
