Saint Paul, MN Landscaping Rules: Rainwater Harvesting (2026)

Minnesota state law does not restrict residential rainwater harvesting. Saint Paul residents may install rain barrels (typically 25 to 100 gallons) at downspouts to collect roof runoff for outdoor non-potable uses such as garden irrigation without any permit. Larger cistern systems used for indoor non-potable purposes such as toilet flushing or laundry are regulated under the Minnesota Plumbing Code (Chapter 4714) and require a plumbing permit through the city. Cross-connection protection is mandatory wherever harvested water shares any plumbing with the potable water supply. Saint Paul has been a leader in municipal-scale rainwater reuse, operating a 27,000-gallon cistern at a Metro Transit facility and a 675,000-gallon underground storage system at Allianz Field developed in partnership with the Capitol Region Watershed District (CRWD). The CRWD offers cost-share grants for residential and commercial green infrastructure projects including rain gardens, cisterns, and permeable pavement in its service area, which includes much of Saint Paul. The Minnesota Board of Water and Soil Resources Lawns to Legumes program also provides reimbursements for qualifying residential stormwater and pollinator plantings.