According to Brad Lancaster's calculations, "Tucson's average rainfall actually exceeds our current municipal water use." And, despite an increase in public interest surrounding the potential of a water source that quite literally falls from the sky, experts admit that when rainwater is led via storm drains to the now-often-dry Santa Cruz, Pantano, and Rillito rivers, a vast majority of it is lost to evaporation.
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According to the local nonprofit Watershed Management Group, using rainwater to irrigate provides additional benefits, as well "The traditional thinking is that green infrastructure at the site scale is not going to have an impact," says WMG's executive director, Lisa Shipek, but she adds that research conducted recently by the organization suggests that this is simply not the case.