District of Columbia, DC Landscaping Rules: Rainwater Harvesting (2026)

Unlike many western states, DC actively promotes residential rainwater harvesting as a stormwater management and sustainability tool. The Department of Energy and Environment (DOEE) RiverSmart Homes program subsidizes rain barrel installations (typically 50-60 gallon barrels) for DC homeowners at roughly $45 out-of-pocket, down from retail prices near $200. The program also supports rain gardens, permeable pavers, bayscaping, and shade trees, all as Best Management Practices (BMPs) that earn Stormwater Retention Credits (SRCs) under the DOEE Stormwater Management Regulations (21 DCMR 5). Rain barrels up to 500 gallons that collect from roof downspouts and dispense via gravity spigot to garden hose are exempt from plumbing permits. Larger cisterns (over 500 gallons) or any system connected to indoor plumbing (for toilet flushing, laundry, or other non-potable uses) require a DC Department of Buildings plumbing permit and backflow prevention per the DC Plumbing Code. Potable use of harvested rainwater requires DC Health approval and treatment to drinking water standards — essentially never done residentially. Rain barrels cannot be placed in public space or front setbacks visible from the street without historic district review in historic neighborhoods. The Stormwater Retention Credit Trading Program allows property owners to generate and sell credits for installed BMPs, creating a market incentive for harvesting.