Yes. Rain barrels are completely unrestricted in Washington; permits apply only to large cistern systems.
What Washington law says
Washington draws a line by system size. Standard rain barrels unrestricted. Large cisterns require a water right permit. If you are putting one or two barrels under a downspout, nothing about Washington law affects you.
How much water a Washington roof can collect
Washington averages about 38 inches of rain per year. On a typical 1,200 square foot roof at 85% collection efficiency, that works out to roughly 24,100 gallons a year currently running into your storm drain. A single one-inch storm delivers about 635 gallons, enough to fill 13 standard 50-gallon barrels.
Average annual rainfall in Washington.
Gallons per year from a typical 1,200 sq ft roof.
Approximate annual value at municipal water rates.
Your roof and rainfall will differ; run your exact numbers in the rainwater calculator.
The right setup for Washington’s climate
Washington averages around 38 inches of rain a year, a moderate climate where a standard 50-gallon barrel with a diverter refills reliably between garden waterings. Most households here are well served by the classic starter setup.
Rain Wizard 50 + Diverter Kit, reviewed against our independent testing criteria. See all six models side by side.
Common questions
Is it illegal to collect rainwater in Washington?
Do I need a permit for a rain barrel in Washington?
Does Washington offer incentives for rainwater harvesting?
Sources
- Rainplan, 50-State Rainwater Collection Guide (2026)
- State statutes and water agency guidance for Washington
- NOAA National Centers for Environmental Information, annual precipitation normals
- US EPA WaterSense, Outdoor Water Use fact sheet
Educational content, not legal advice. Laws change; confirm current rules with your state water agency.