The United States is confronting a growing water shortage: roughly half the country was already facing drought conditions in March. Climate change is worsening the problem — higher temperatures and more intense, sporadic rainfall lead to runoff rather than slowly recharging soils and aquifers. Scientists warn this could intensify: NASA says the American Southwest and Central Plains may face “megadroughts” after 2050, potentially longer and more severe than any in the past millennium.
When supplies run low, officials typically impose use restrictions, raise prices or seek new sources. In many arid regions, however, options are limited. “There’s a water demand in arid places that has to be met. We cannot just say, ‘Well, there’s no water for Southern California or for Arizona or for West Texas,'” said Bridger Ruyle, an environmental engineer at New York University.
That demand has renewed interest in a source once dismissed for its “yuck factor”: treated wastewater. Surveys show people in small communities would accept higher utility bills for local wastewater recycling if it meant avoiding strict water limits. “This can be a sustainable great idea for some communities, because essentially you’re really taking the most out of the supply that you’re naturally given,” said Todd Guilfoos, a water economist at the University of Rhode Island, who ran such a survey.
How wastewater recycling works
Modern sewage systems send water from toilets, showers and sinks to treatment plants. Primary treatment removes solids; secondary treatment uses microorganisms to break down organic pollutants. Those stages make wastewater safe to discharge to the environment but not potable. Tertiary treatment — including ultrafiltration, reverse osmosis and disinfection with ultraviolet light or chemicals like chlorine — is required to make wastewater suitable for drinking or irrigation.
Most US wastewater plants lack full tertiary treatment. The Environmental Protection Agency says American facilities treat about 33 billion gallons per day but recover only about 7% of that for reuse. Closing that gap would require large investments to upgrade plants and distribution systems. “Rather than building another dam or drilling another well or putting another catchment, we are already treating water. This is one of the most economical solutions to save water,” said Samuel Sandoval Solis, a water resources expert at the University of California, Davis.
Overcoming the “yuck factor”
Public opposition has blocked reuse projects before. In the 1990s San Diego shelved a program amid political backlash and headlines branding it “toilet-to-tap.” Attitudes have shifted as scarcity has grown more acute: San Diego is now building a reuse facility intended to supply 30 million gallons a day — about one-third of its water supply by 2035. Similar initiatives are underway across drought-impacted states including California, Arizona, Texas and Florida.
“I don’t think 20 years ago anybody thought of recycling wastewater,” said Metin Duran, a microbiologist at Villanova University. For those who still resist direct reuse, there is a practical reality: many Americans already consume water that has passed through wastewater systems indirectly. Half of US drinking-water treatment plants draw from rivers or streams downstream of wastewater discharges — a phenomenon called de facto reuse. “Anyone thinking, ‘I’m not using recycled water’ — most of the people are already doing it one way or another,” Solis said.
Costs and tradeoffs
Implementing potable reuse at scale is expensive. Guilfoos found respondents in towns of fewer than 10,000 people would, on average, pay about $49 a month extra on top of existing water bills to fund a local reuse program. That level could cover the operation and management of tertiary treatment but not the big capital costs of upgrading aging infrastructure, laying new pipes, and installing pump stations. San Diego’s first construction phase alone is estimated to cost $1.5 billion, relying on a mix of local, state and federal funding.
There are environmental and technical tradeoffs as well. Advanced treatment can be energy intensive—the more thorough the purification, the higher the power demand. Recharging aquifers with recycled water also raises concerns about disturbing heavy metals or other contaminants in soils, which could harm human health and ecosystems. “We need to be very careful about addressing one problem and having that not cause a different downstream problem,” Ruyle said. “It’s not just kicking the can down the road for a new problem that we’ll find out about in 10 years.”
Wastewater reuse is not a silver bullet for water scarcity, experts emphasize, but climate change and shrinking alternatives make it an increasingly attractive and practical part of the toolkit. “I don’t think there’s any future in which you can just say, ‘Oh, no, we don’t need this at all,'” Ruyle said.