About half of the United States is facing drought conditions in March, and climate change is making dry spells hotter and more intense. Rain increasingly falls in heavy bursts that run off hardened ground instead of recharging soils and aquifers. Scientists warn the American Southwest and Central Plains could face “megadroughts” after 2050 — potentially longer and more severe than any in the past 1,000 years, according to NASA.
When water runs short, authorities typically limit use, 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 is renewing interest in wastewater recycling — treating sewage so it can be reused for drinking, irrigation or groundwater recharge. Public support has often been constrained by a “yuck factor,” but attitudes are shifting as shortages grow. A survey of people in communities under 10,000 found respondents would pay about $49 a month extra to fund a local reuse program, rising among those with water shortage experience or knowledge of reuse, according to Todd Guilfoos, a water economist at the University of Rhode Island.
How wastewater recycling works
Modern sewage treatment began in the early 20th century. Conventional plants perform primary treatment to remove solids and secondary treatment using microbes to break down organic pollutants. Those steps typically render wastewater safe to discharge but not potable. Tertiary treatment—ultrafiltration, reverse osmosis and disinfection with ultraviolet light or chemicals like chlorine—removes pathogens and dissolved contaminants to make reclaimed water suitable for drinking or agriculture.
Most US wastewater plants aren’t equipped for tertiary treatment. The Environmental Protection Agency reports plants treat about 33 billion gallons per day but only recover roughly 7% for reuse. Closing that gap would require major investments to upgrade facilities and distribution systems. “Rather than building another dam or drilling another well… 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 UC Davis.
Overcoming opposition
Public opposition has blocked reuse projects in the past. San Diego in the 1990s abandoned a plan amid backlash over so-called “toilet-to-tap” coverage. But scarcity has changed perspectives: San Diego is now building a reuse facility expected to supply about 30 million gallons a day — roughly one-third of the city’s water — by 2035. Similar projects are underway across drought-prone states such as California, Arizona, Texas and Florida.
Experts also note that many Americans already consume water that was indirectly reused. Half of US drinking-water 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 people are already doing it one way or another,” Solis said.
Costs and tradeoffs
Implementing reclaimed-water systems is expensive. The $1.5 billion first phase of San Diego’s plant illustrates the scale; federal and state funds often help cover capital costs. The monthly fee cited in Guilfoos’s survey could typically fund operation and tertiary treatment, but not the large upfront investments in new pipes, treatment facilities and pump stations.
There are environmental and technical tradeoffs. Advanced treatment can be energy intensive — the more thorough the process, the more power required. Recharging aquifers with treated wastewater can also mobilize heavy metals or other contaminants in soils, creating potential health and ecological risks. “We need to be very careful about addressing one problem and having that not cause a different downstream problem,” Ruyle said.
Not a silver bullet
Scientists agree wastewater reuse is not a panacea for water scarcity. It carries costs, energy demands and environmental considerations. Still, with climate change reducing other options, reuse is becoming a practical and sometimes necessary part of water portfolios in many communities. “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.
Edited by: Jennifer Collins