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The Role of Water in Making Cities More Livable

In the second of a two-part interview, urban water expert David Sedlak, a civil and environmental engineering professor at the University of California, Berkeley, talks about technologies that are helping to fuel a new revolution in urban water systems.

Written by Tara Lohan Published on Read time Approx. 7 minutes
A worker passes rows of tubes used in the reverse osmosis process at the Carlsbad Desalination Project in Carlsbad, Calif. The plant will help determine the future of seawater desalination in the U.S. The billion-dollar project is only the nation's second major seawater plant.Gregory Bull, AP

It’s been two years since urban water expert David Sedlak’s book, “Water 4.0: The Past, Present and Future of the World’s Most Vital Resource,” was published. And Sedlak has already seen a lot of progress being made with innovations that can aid water supply and the public and political will to implement them.

Sedlak, professor in the department of civil and environmental engineering at the University of California, Berkeley, co-director of Berkeley Water Center and deputy director of the National Science Foundation’s Research Center for Re-Inventing the Nation’s Urban Water Infrastructure (ReNUWIt), talked to Water Deeply about the future of our urban water supply.

In the second of a two-part series, Sedlak explores the rising interest in direct potable reuse, the possibilities for more desalination and the role of water in making cities more livable.

Water Deeply: Your book, “Water 4.0,” came out in 2014. Is there anything that has happened on the water front since that has surprised you?

David Sedlak: Something that has advanced a lot since I wrote the book is what people refer to as direct potable reuse. It’s the idea that you can essentially hook up your wastewater treatment plants to your drinking water treatment plant without first putting the water into the environment.

The Orange County project and all the other ones I talked about store that highly treated water in a groundwater aquifer before it is pumped up and used as a drinking water source. What we are seeing now, driven not only by the drought in California but the drought in Texas, is a movement toward direct potable reuse.

I think that’s something I didn’t expect to see happening so quickly. It certainly changes things a bit with respect to the feasibility of water recycling in places like Los Angeles and San Diego. In Los Angeles, for example, the big sewage treatment plants are located close to the ocean. The water supply system, if you’re going to store water in the ground, you’d have to pump it all the way inland, and that would cost billions of dollars to build a pipeline to pump that water inland. And so if Los Angeles could use direct potable reuse, it could suddenly be a more viable option for growing the region’s water supply.

There is a [direct potable reuse] project in El Paso, Texas, which is planning to do this in the next couple of years.

Water Deeply: Your book was published before the desalination facility in Carlsbad went online. What are your thoughts now that it’s up and running – was it a good investment for the region, and what does the future hold for desalination in California?

Sedlak: I think that most people are taking a wait-and-see view of the desalination plant and the other ones that have been proposed. I’ve always seen desalination as an option of last resort, when you have tried everything else and it’s failed.

I think we may see a few more desalination plants in communities that have exhausted all their other options. Santa Barbara and the Salinas Valley are looking more closely at desal because they don’t have too many other options. They’ve done a good job with conservation and they don’t have very many options for expanding their imported water supplies. But I think those communities could and should try harder with water recycling before they try desal plants.

Water Deeply: Are there technological advances that would make desalination a better option in the future?

Sedlak: What I’m particularly excited about is that now we are seeing the Department of Energy turn its attention to desalination. The DOE proposed something they call “pipe parity,” and they are looking to create a project to reduce the cost of desalinated seawater by 75 percent.

If that project succeeds or partially succeeds, it could be a game changer because suddenly desalinated water could be as cheap or cheaper than many of the other supplies, and it would really change the way we think about seawater desalination as a drinking water supply.

Water Deeply: Are they targeting a specific area of the process to reduce that cost? Like the energy input?

Sedlak: They talked about going after every aspect of building and operating a desalination plant. There is not a silver bullet waiting out there with forward osmosis or carbon nanotubes or some sort of new membrane material.

Water Deeply: Is there any opportunity to use renewable energy in the desalination process?

Sedlak: In the book I talked about the way in which Perth, Australia, used the construction of desalination plants as a motivation for building a wind farm and a solar energy farm, because you have this new electricity demand coming online, and you can use it to finance the creation of renewables.

I think here in California we have plenty of reasons to expand our renewable power portfolio and I’d hate to see it be a one-for-one trade; that is, we just keep building these energy-consuming desal plants at the same time as we keep building more solar plants, and we don’t make any progress.

In a way, it could just put more demand on the electricity grid and prevent us from reaching our greenhouse gas emission goals.

Water Deeply: The California Treasurer has cited a $24 billion funding gap for California’s water infrastructure – how do we start to close that gap?

Sedlak: I’m a lot more optimistic about that funding gap question in California than I am in Michigan or other parts of the country. Here, in the last drought, the issue of water security was on everyone’s mind when the voters approved Proposition 1, so there is bond funding on the way to encourage cities to invest in water infrastructure.

I think we are also seeing the public being a lot more willing to consider investments in water, and that’s because elected officials now see it as part of their job to ensure water security for their communities. And the public realizes that without a water supply, the economy can be crippled.

People in California have started to get the message, and it’s a lesson for the rest of the country that when we talk to the public about the water infrastructure funding gap, they have to realize that it’s not just an occasional leaky pipe, it is something that endangers the vitality of the community.

Water Deeply: Are there any changes we should be thinking about in the way in which utilities can charge for water or the pricing structure?

Sedlak: I think at first it’s going to take a certain amount of education and we’re going to look toward the electric power utilities. I think it was the CEO of Duke Energy who came out and told people, “You’re going to use less electricity in the future, and I’m going to charge you just as much money for it.” People have to realize that water supply is not really on a cost-per-volume-of-water-delivered basis, it’s the service of having the water when you need it.

In some ways by setting the tiered block pricing to discourage people from overusing water, we’ve sent the wrong message. The message should be that there is more or less a fixed price to provide you with water service, and then if we’re going to penalize you for using too much water, it should just be a straight penalty.

I think the problem is the way Proposition 218 works and the way that we have set up the legal structures. I don’t see an immediate solution to it because of the legal precedent and all the anti-tax groups.

Water Deeply: Is there anything else that will be important for urban water systems as we look to the future?

Sedlak: The role of water in making cities livable. There is this tension that I’ve started to notice during the drought between water conservation and urban greenery and aesthetics. Here at the university, I’ve had discussions with the groundskeepers, and they’d love to pull out all the lawns to save water, but you realize that those are places that make a city more pleasant to be in, and all of that greenery also serves a role in keeping that city cool.

And so if we pull out too many of the shade trees and rip out the shrubbery, it’s going to get hotter in cities, and people are going to use more air conditioning, and it’s going to send us backward in terms of our goals of conserving energy.

I think we need to think about water as an asset, not just for cooking and bathing, but also for making our cities pleasant places to live in. I’m not defending great big lawns in the middle of the desert or golf courses in places where there are water shortages, but certainly in our dense urban cores, that water is used in a way that makes people’s lives more pleasant and also ultimately saves us energy.

And one other thing – people all over the world pay careful attention to what happens in California, and what we do with water recycling and stormwater capture and water conservation, and everything that we’ve talked about here.

It influences the way people think, not only in Australia and the Mediterranean, but in other places where water security is an issue, such as Brazil or Singapore or China or India. They look to us for leadership here, and I think we are a living laboratory for the way that much of the rest of the world will manage its water in the future.

Read the first part of this series here.

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