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This City’s Recycled Wastewater Is Too Pure to Actually Drink – Mother Jones
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This City’s Recycled Wastewater Is Too Pure to Actually Drink – Mother Jones


David Paul Morris/Bloomberg/Getty

This story was originally published in Wired This is part of the Climate Desk collaboration.

On a dusty hilltop San Diego’s future drinking water flows through a complex and loud network of pipes, tanks, and cylinders. The North City Water Reclamation Plant turns very non-drinkable wastewater into a water so pure that it would cause serious health problems if consumed without further treatment. 

The system first uses ozone to kill bacteria and viruses in the wastewater. The system then pumps the water through filters containing coal granules to trap organic substances. The water then passes through fine membranes to capture any remaining solids or microbes. “The pores are so small, you can’t see them except with a really powerful microscope,” says Amy Dorman, deputy director of Pure Water San Diego, the city’s initiative to reduce its reliance on water imported from afar. “Basically, they only allow the water molecules to get through.” 

To be sure, the next step is to use UV light to destroy any trace contaminants or microbes. The end result is water in its purest form—Too pure, in fact. The last phase is “conditioning” the liquid by adding minerals back to it. Without it, the water could leach copper from pipes. If you drank it, it’d soak up your electrolytes like a sponge. 

If that all sounds like a rather convoluted way to get drinking water, that’s because the American West is facing a rather convoluted climate crisis. San Diego—and the rest of Southern California—have historically relied on water from Northern California and the Colorado River. But they’ve always been at the end of the line. The river hydrates 40,000,000 people in Colorado and Wyoming, Arizona, Nevada, Nevada, New Mexico, and Utah. under a historic droughtThis is a sign of worse water scarcity as the climate heats.

San Diego must figure out how to make more water with less. The Pure Water program is designed to provide pure water. more than 40 percent of the city’s water from local sources by the year 2035 by reusing water recycled from homes and businesses. This means that water has flowed through toilets, sinks, and washing machines. “We’re diversifying the portfolio,” says Todd Gloria, San Diego’s mayor. “We’re heavily dependent upon water that comes from very far away, and that’s a problem that we have to address.”

The project is still in its infancy, and the North City Water Reclamation Plant purification system is a laboratory. Engineers have been testing different membranes to see which one works best for the wastewater they receive. The city is also building a larger facility across the street. It will be operational in 2025 and will eventually produce 30,000,000 gallons of water each day. Phase two, which involves the construction of additional facilities, will eventually bring production up to 83 million gallon per day. The Pure Water project is being funded by federal and state grants, as well as loans from the Environmental Protection Agency.

Although the water-recycling revolution in San Diego is just beginning, its supporters hope it will spread across the American West. Legislators in the US House of Representatives submitted a bill that would channel $750 million to water recycling projects across 17 western states until 2027. (The bill hasn’t made it past committee.) “This is beginning to be our new normal—88 percent of the West is under some degree of drought,” Representative Susie Lee (D-Nevada) told Wired in July. “Lake Mead is at the lowest level it has been at since the Hoover Dam was constructed. And the Colorado River has been in a drought for more than two decades.”

The technology to recycle water on a large scale already exists—it’s been around for half a century, in fact. But the problem is that it can cost billions to build a recycling facility, and you can’t just copy-paste a particular plan from one municipality to the next. Because water quality is different, the North City Water Reclamation Plant experimented with different types and materials. The San Diego facility has a different water quality than what operators might have in New York. Because recycling plants require high pressure to pump water through fine membranes, they are expensive to operate. It takes a lot more energy to transport water from the northern regions to Southern California.

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. 

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. This could be a motivating factor for voters to support 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.” 

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 more likely than other hazards that city planners need to consider, such 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.”

Southern California cities are becoming more 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 50 million gallons per day of fresh water. Los Angeles’ 150-acre reservoir is home to the Los Angeles Times. Tujunga Spreading Grounds act like a giant sponge, soaking up stormwater that then percolates into an aquifer below. Similarly, greenspaces designed to collect water along roadsides in Los Angeles do the same thing and gather it into underground tanks. 

These projects predict one of the strange ways climate change will affect the hydrological cycle. Rains in Southern California may come less often but will dump more precipitation when it does. A warmer atmosphere holds more water. The idea is to catch the bounty when it arrives and store it underground for when it’s needed. “The attitude down here is that we have to have a bunch of different tools in the toolbox,” says Dorman of Pure Water San Diego.

To be clear, these technologies are in no way a substitute for the smarter use of water—or really, Disable of water. Between 1990 and 2010, water use in California actually plummetedWater-saving technology like low-flow toilets has helped reduce water consumption by reducing the amount of water needed to wash your clothes. But it’s also been thanks to behavioral change, like people switching from green lawns to yards full of drought-tolerant native vegetation. 

The challenge will be the vagaries of climate change—the drought in the West could lift soon, or the region might be in the midst of a decades-long megadrought. “The old search for traditional types of water supply from rivers and groundwater is not going to be sufficient in a world of climate disruption,” says Kiparsky. “We need to be thinking in totally different ways, because the old ways just don’t work anymore, and the smart utilities like San Diego are seeing that.”

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