Washington County, OR Landscaping Rules: Rainwater Harvesting (2026)

Oregon law permits collection of rainwater from rooftop catchment for non-potable use without a water right, per Oregon Water Resources Department policy confirmed in 2009. Washington County allows residential rain barrels and cisterns for garden irrigation, lawn watering, and toilet flushing without special county permits for simple systems. Systems connecting to indoor plumbing require plumbing permits under Oregon Plumbing Specialty Code (OAR 918-750); potable use requires an engineered treatment system compliant with Oregon Building Codes. Cisterns over certain size (varies, often 5,000 gallons) may require building permits. Clean Water Services encourages rainwater catchment as part of its stormwater management toolkit and has run rebate programs in past years — cisterns qualifying as detention can partially offset post-construction stormwater requirements. HOAs in Bethany, Reedville, and Hillsboro's Quatama commonly permit screened rain barrels; some specify placement (side/rear yard). Collection from driveways, patios, or ground is not considered rainwater under state policy and flows as stormwater subject to CWS rules. Oregon is water-rich west of the Cascades (40+ inches annual precipitation in Washington County), making catchment highly practical October-May.