But if you’re able to recycle water on a large scale, you’ve got a powerful hedge against drought. “That’s an extraordinarily reliable supply, being able to access that flow of wastewater, clean it up, and then use it to offset the need for other supplies,” says Michael Kiparsky, director of the Wheeler Water Institute at UC Berkeley. 

And really, water recycling is an investment. As water grows scarcer in the West, it’s also getting more expensive. The cost of San Diego’s imported water has tripled in the past 15 years. That could be a powerful factor for voters when it comes to supporting water recycling projects. “People’s bills are also extremely motivating, right?” asks Gloria. “When you explain to them that if we can control this resource ourselves—that we don’t have to rely on water managers north of us, or multistate agreements, water-transfer agreements with other counties—when we can control it ourselves, there is some greater ability to control costs.” 

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Historically, though, policymakers have had to battle recycled water’s “ick factor.” Folks may not trust it, even though it’s astonishingly pure. (I’ve tried it before—it was refreshing and didn’t kill me.) But Gloria points out that if your municipality is drawing water from the Colorado or some other river, and you’re downstream from other municipalities doing the same, you’re already drinking recycled water. “Everyone else grabbed that water, used it, discharged it back, and it’s on its way down here,” says Gloria. “So if you think that you aren’t already participating in some form of water reuse, you’re probably mistaken.”

But just as with picking stocks, it’s safer to hedge your bet with a diverse portfolio of resources rather than having a single asset. Any city that’s banking on one river or lake as its sole source of water is asking for trouble, because the more frequent and intense droughts that come with climate change will bring market volatility on a grand scale. “Water right now, I think, is our greatest natural challenge,” says Adrian Borsa, a geophysicist at the Scripps Institution of Oceanography in San Diego, who studies how aquifers store water. Drought is a more certain near-term risk to the West than other hazards that city planners have to account for, like earthquakes. “It’s not anymore, ‘Oh, we’re going to get this magnitude 7½ on the San Andreas Fault.’ That’s going to happen sometime, but for sure we are going to face water scarcity challenges.”

So Southern California cities are getting creative in diversifying their portfolios. The Carlsbad Desalination Plant processes seawater much the same way as a recycling plant does—by passing it through membranes. It provides San Diego County with 50 million gallons of fresh water a day. In Los Angeles, the 150-acre Tujunga Spreading Grounds act like a giant sponge, soaking up stormwater that then percolates into an aquifer below. Elsewhere around LA, specially designed greenspaces along roadsides do the same, gathering water into underground tanks.