Pima County, AZ Landscaping Rules: Rainwater Harvesting (2026)

030(R) of the Pima County Zoning Code says rainwater harvesting systems, meaning tanks and cisterns that collect and store rainwater for reuse on the same property, are permitted in all zones subject to specific conditions. Any exposed cistern opening must be screened with corrosion-resistant metallic fine mesh to keep mosquitoes out, and large openings must be securely fastened to prevent accidental drowning. Overflow or discharge from a system cannot adversely affect adjacent property or a public right-of-way. Cisterns follow the underlying zone's yard setbacks: front setbacks match the main-structure requirement, rear setbacks match the accessory-structure requirement, and side setbacks match the accessory-structure requirement, except that zero lot-line siting is allowed for cisterns eight feet or less in height (excluding piping) on lots of eight thousand square feet or less.

Two size-based exemptions matter most for homeowners: cisterns forty-eight inches or less in height and width, excluding piping, are exempt from the underlying zone's minimum yard setback distances entirely, and all cisterns are exempt from the zone's maximum lot-coverage calculation regardless of size. On smaller single-family lots (under seventy-two thousand square feet), if more than two cisterns are visible in a front or side yard from a single point on the abutting street, they must be screened behind a wall, fence or hedge at least five feet high.

Because the county reaches only unincorporated land, Tucson, Marana, Oro Valley, Sahuarita and South Tucson residents fall under their own city rainwater rules instead. 030(S).