The California Building Standards Law requires a state agency that adopts or proposes adoption of a building standard to submit the building standard to the California Building Standards Commission for approval and adoption. Existing law makes the commission responsible for the publication of an updated edition of the California Building Standards Code every 3 years. Existing law requires the Department of Housing and Community Development to propose to the commission the adoption, amendment, or repeal of building standards for, among other things, the installation of recycled water systems for newly constructed single-family residential and multifamily residential buildings, as specified. This bill would require the department to review current building standards, conduct research, and develop recommendations regarding building standards for the installation of rainwater catchment systems for nonpotable uses in newly constructed residential dwellings and would authorize the department to propose related building standards to the commission for consideration, as specified. The bill would authorize the department to expend moneys from the Building Standards Administration Special Revolving Fund for the above-described purposes, upon appropriation by the Legislature, as specified. The bill would require the department, on or before January 1, 2027, to provide a report to specified committees of the Legislature regarding the outcomes of its research and the recommendations developed.