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Portable Potables: How To Fight Drought By Reusing Water


Desalination is just one way of tackling the drought. Another technique to conserve water is quite simply to reuse it. David Sedlak is professor of civil and environmental engineering at the University of California Berkeley. David, welcome to the program.

DAVID SEDLAK: Thank you for having me, Audie.

CORNISH: Now, as we just heard talked about in Nate Rott's piece, desalination is expensive and has some environmental issues. There are some other options you've written about, water recycling and also rainwater harvesting. Let's talk about rainwater harvesting. I understand that in parts of California, people are starting to try this out.

SEDLAK: Well, your listeners may be familiar with rainwater harvesting on a small scale, like when someone puts a barrel on the end of a rain gutter and harvests the water and uses it in their garden. And that's a fine approach if you live in a temperate climate where it rains all year round. But here in California where, if we're lucky, we get four or five big storms a year, we have to be a little bit more creative if we want to capture all that water and put it back underground so it can be part of the groundwater supply.

So in Southern California, the water utilities are actually making large investments in systems that hold the water in ponds and then, over the next few months, it can gradually be fed into the drinking water aquifers. The City of Los Angeles is starting to buy up former gravel quarries where they can hold the water as they slowly percolate it into the ground.

CORNISH: Where is the technology on this kind of thing? I know, for example, an underground water storage facility in Moorpark, California, cost 150 million and doesn't work in the drought.

SEDLAK: Storm water capture and recharge systems are really in their infancy when we talk about building them on the kind of scales that people are planning to use in Southern California. We really have to understand the quality of the water coming off of city streets, ways to improve it before we put it underground and maybe more importantly, ways to make sure that we recover all of the water that we put into the aquifer.

CORNISH: And the other idea, water recycling. Talk about some clever approach to the capture and reuse of drinking water on a mass scale.

SEDLAK: When we talk about water reuse, there's non-potable water reuse and potable water reuse. Non-potable water reuse has been with us for a long time. That's the idea that you can take the water that comes out of a sewage treatment plant, add some more chlorine or disinfectant and then use it for things like golf course irrigation or industrial boilers or cooling systems.

Unfortunately, it's actually expensive when you try to expand it beyond the golf courses or power plants and oil refineries that are located close to a sewage treatment plant. And so, when we talk about water reuse, one of the best approaches may be potable water reuse. That is taking the water that comes out of a sewage treatment plant and treating it some more, to a point where it can actually be introduced back into the drinking water supply.

CORNISH: In what ways can people do this kind of thing at home? I mean, if you can't wait for your community to adopt this on some mass scale, what approaches do you think make sense?

SEDLAK: The approach that makes the most sense with respect to what someone can do at home is water conservation. There are a lot of things we can do to decrease our water consumption. And the place where the greatest opportunities exist is outdoors. That can include things like replacing a lawn with plants that don't use a lot of water or keeping the lawn and using smart irrigation controllers that can decrease the amount of water applied to the lawn on cloudy or rainy days or only apply lots of water to the parts of the yard that need it most.

CORNISH: David Sedlak, he's a professor of civil and environmental engineering at UC Berkeley and author of "Water 4.0." Thanks so much for talking with us.

SEDLAK: Thank you, Audie. Transcript provided by NPR, Copyright NPR.