The Future of Water Is Recycled Sewage
The Future of Water Is Recycled Sewage
More than a few dystopian fantasies depict a future in which humanity’s water supply derives from recycled human waste. As Frank Herbert imagined it in his 1965 novel "Dune" — now a much-anticipated fall 2021 blockbuster — the humans inhabiting a dessicated, rainless planet must wear “stillsuits”— a rubbery second skin that captures sweat, urine and feces and recycles them into drinking water.
Today, elements of this vision are becoming a reality. While no climate models predict a future without rain on Earth, all show severe disturbances in hydrology: increasingly excessive rain and flooding in some regions, and intensifying drought in others. California has now become a leading example of the latter. Suffering through a prolonged dry period, utilities are increasingly relying on sewage to generate the state's water needs.
Known in industry parlance as “recycled wastewater” and in lay terms as “toilet to tap,” this water source understandably triggers a gag reflex in some consumers — but it shouldn't. Recycled wastewater is quickly becoming the single most important element of a drought-proof water supply in the climate-change era, and it happens to be as pure and delicious as anything you might buy bottled from the Swiss Alps.
In fact, some southern Californians already have been drinking recycled wastewater for years, thanks to a pilot project in Orange County. And the $5.1 billion drought-response package Governor Gavin Newsom announced last week focuses heavily on making this sustainable source more widely available. But this shouldn't remain just another California experiment. The federal government should prioritize infrastructure spending on wastewater recycling facilities, as should the growing number of water-insecure states nationwide, including Texas, which now is also experiencing severe drought, and Florida.
There's no state in our union that faces more economic peril from an unstable water supply than California — and the repercussions will affect all of us. Roughly 80% of the water developed for agricultural and urban use flows to California farms, which in turn grow more than half of all the fruits, nuts and vegetables produced in the US. The dairy cows that graze in California pastures produce 20% of the national milk supply. In 2014, during the last severe drought, the state racked up more than $2 billion in agricultural losses alone.
California farmers have long faced water insecurity — John Steinbeck wrote in his 1952 novel East of Eden that dry years were inevitable in central California and “put a terror on the valley” — but the stresses are now increasingly severe. In the next thirty years, the severity of widespread summer drought is projected to almost triple. Southern California depends entirely on Northern California and the increasingly strained Colorado River to hydrate its lands and 24 million inhabitants. There’s no question that the region needs new water sources to remain habitable.
One option that's been explored is desalination, a filtration method that strips salt from ocean water. In 2015 a $1.5 billion desalination plant was built in Carlsbad, California, that now supplies 10% of San Diego’s water. Since then, many more desalination plants have been sited on the southern and central Californian coast. Yet recycling wastewater is much cheaper: desalinated water costs about $3,000 per acre-foot, while recycled wastewater costs $1,800 per acre-foot.
Both types of water are treated mechanically, pumped through a multi-step filtration process that culminates with reverse-osmosis membranes that pull out impurities — including not just visible particles, but viruses, pathogens, hormone-disrupting chemicals and salt. The most difficult impurity to remove is, in fact, salt (which isn’t suspended in water, but dissolved). Sewage is easier and cheaper to filter than ocean brine simply because it has far lower salinity and therefore requires less energy to pump through the membranes. It’s also more universally available; not every farm or city is located next to an ocean, but everybody has sewage.
In 2008, Orange County Water District opened a $490 million toilet-to-tap facility (which they prefer to call showers-to-flowers) next to the county’s sewage plant and began to shift the paradigm. It pumped 70 million gallons of recycled sewage water into the underground reservoirs that supply Orange County’s taps. The plant has been so successful that production was expanded to 100 million gallons a day in 2018, making it the world’s largest recycled wastewater plant; another expansion to 130 gallons a day was recently announced. Orange County is soon to be outdone by Los Angeles County, which has proposed a 150-gallon a day facility that could come online as soon as 2023.
Singapore and Israel, among other countries with limited freshwater resources, have been recycling their wastewater for decades while the US resisted. Twenty years ago, Los Angeles County spent millions on a recycled wastewater plant only to shut it down within weeks of its opening after an outcry from residents who objected to the idea of drinking their own sewage. Similar objections have scuttled efforts to build recycled wastewater plants in San Diego.
I get it: Even amid the desperation of drought, consuming your own waste is nobody’s first choice. Paul Rozin, a social psychologist at the University of Pennsylvania who’s researched consumer response to toilet-to-tap programs told me that “accepting recycled wastewater is kind of like being asked to wear Hitler’s sweater. No matter how many times you clean the sweater, you just can’t take the Hitler out of it.”
Here’s what’s changed: The realities of climate change, and even Herbert’s dystopia, are increasingly upon us. The technology has gotten better, too, producing an excellent product. I’ve drunk the water flowing out of both of the Carlsbad and Orange County plants, water that hours earlier had been ocean brine and sewage. Both tasted crystal clean without a trace of their origins. No water expert I’ve interviewed questions that the single biggest source of new water supply going forward will be recycled wastewater. Our state and federal lawmakers are now obligated to prepare and adapt our infrastructure to this new reality.