Maryland Rainwater Harvesting Legal Statewide

Maryland does not restrict residential rainwater collection. Systems are governed statewide by the Maryland Plumbing Code (based on the IPC) Chapter 13, Section 1303, which addresses construction, installation, and treatment of nonpotable rainwater collection systems. The Maryland Department of the Environment publishes Stormwater Design Guidance for rainwater harvesting and lists rain barrels and cisterns among approved Environmental Site Design practices under COMAR 26.17.02. Indoor reuse is generally limited to nonpotable applications such as toilet flushing, cleaning, and laundry. Local jurisdictions may offer incentives or impose construction permitting but cannot prohibit collection.

Installing a system that fails to meet plumbing code cross-connection, labeling, or backflow requirements can result in inspection failures, correction orders, and fines from local code officials.