South Dakota state law: rainwater harvesting

South Dakota follows the prior-appropriation doctrine under SDCL Title 46 (Water Rights), administered by the South Dakota Department of Agriculture and Natural Resources (DANR) Water Rights Program. The state does NOT have a Colorado-style historical prohibition against residential rainwater capture. SDCL 46-1-6 carves out 'domestic use' from the water-right permit requirement, defined to include water for household purposes, lawn and garden watering, and watering of livestock not for commercial sale. Capture of rainfall from a residential rooftop into rain barrels or above-ground cisterns for outdoor irrigation is consistent with this domestic-use exemption. Large-scale capture intended to serve as the primary potable supply, or capture that intercepts a defined natural watercourse, can trigger DANR review. Connections of harvested rainwater into the indoor potable plumbing system (for toilet flushing or other non-potable interior use) require compliance with the locally adopted Uniform or International Plumbing Code, including backflow prevention to protect the public water supply. The DANR has no statewide rain-barrel registration program. Some municipal stormwater programs encourage rain barrels as part of MS4 stormwater BMPs.

Residential rain-barrel collection for domestic use is not, in itself, a violation. Improper cross-connection of harvested rainwater into the potable plumbing system without code-compliant backflow prevention can trigger plumbing-code enforcement (local building department) and potential cross-connection penalties under the city's water utility ordinance. Large-scale, non-domestic capture without a DANR water-right permit can lead to a DANR cease-and-desist and civil penalty under SDCL Title 46.