Rainwater Harvesting Potential Maps

Abstract

Alternative waters are sustainable sources of water, not supplied from fresh surface water or groundwater, that offset the demand for freshwater. Alternative water can serve as a vital water supply to federal agencies in support of water resilience by providing diverse water sources. One type of alternative water, rainwater harvesting, involves capturing, diverting, and storing rainwater from rooftops for later use. Uses for rainwater include landscape irrigation, ornamental pond and fountain filling, cooling tower make-up, and toilet and urinal flushing. The Federal Energy Management Program has developed a series of alternative water source maps. The first map, developed in 2015 and updated in 2019, is a state-level rainwater harvesting regulations map that visually represents the rainwater harvesting policies across the country and provides general information on state programs, if applicable. This map allows the user to quickly discern where rainwater harvesting is supported and regulated by the state. As a complement to this first map, Pacific Northwest National Laboratory (PNNL) created two additional rainwater harvesting maps to help federal agencies strategically identify locations in the U.S. that are conducive to rainwater harvesting projects. The first map shows the relative potential for capturing rainwater for any use. The second map specifically identifies areas in the U.S. that have potential for supplying rainwater for irrigation.