The United States is facing a worsening water shortfall: by March roughly half the country was experiencing drought. Climate change is amplifying the problem, with hotter conditions and more intense, uneven rainfall that runs off the land instead of slowly recharging soils and aquifers. Scientists warn the trend could deepen — NASA projects parts of the Southwest and Central Plains may suffer extended, severe megadroughts after 2050.
When supplies tighten, water managers usually turn to restrictions, price signals or new sources. In many dry regions, however, those choices are limited. As Bridger Ruyle, an environmental engineer at New York University, points out, people still need water in places such as Southern California, Arizona and West Texas, so alternatives must be found.
One increasingly practical option is treated wastewater. Once dismissed for its so-called yuck factor, recycled water is gaining new support as scarcity grows. Surveys show that people in small communities may accept higher utility bills if it means avoiding strict curbs on water use. Todd Guilfoos, a water economist at the University of Rhode Island, who ran such a survey, says recycling can be a sustainable way for communities to make the most of the supply they already have.
How it works
Sewage from toilets, showers and sinks flows to treatment plants where a sequence of processes removes contaminants. Primary treatment separates solids; secondary treatment uses microbes to break down organic matter. Those stages render wastewater safe enough to release into the environment but not fit for drinking. Tertiary treatment — ultrafiltration, reverse osmosis and disinfection with ultraviolet light or chemicals such as chlorine — is required to produce water suitable for irrigation, aquifer recharge or even potable uses.
Most U.S. wastewater plants do not have full tertiary treatment. According to the Environmental Protection Agency, U.S. facilities treat about 33 billion gallons per day but reuse only about 7 percent of that. Closing that gap would require large investments in treatment upgrades and distribution infrastructure. Samuel Sandoval Solis, a water resources expert at UC Davis, notes that recycling is often more economical than building new dams or drilling more wells because the water has already been collected and treated to some degree.
Facing the yuck factor
Public opposition has stopped reuse projects in the past. In the 1990s, San Diego abandoned an effort amid political backlash and headlines deriding the idea as toilet-to-tap. Attitudes have shifted with increased scarcity: San Diego is now constructing a reuse facility planned to deliver about 30 million gallons a day, roughly one-third of the city’s supply by 2035. Other drought-impacted states, including California, Arizona, Texas and Florida, are pursuing similar projects.
For many Americans the distinction between recycled and conventional sources is already blurred. Half of the nation’s drinking-water plants draw from rivers or streams downstream of wastewater discharges; this de facto reuse means indirect consumption of treated effluent is already common.
Costs and tradeoffs
Scaling up potable reuse is expensive. In small towns of fewer than 10,000 residents, Guilfoos found people would on average pay about $49 a month extra to fund a local reuse program. That could cover operation and management of tertiary treatment but not the major capital costs of upgrading aging plants, laying new pipelines and installing pumps. San Diego’s first construction phase alone is estimated at $1.5 billion and relies on a mix of local, state and federal funding.
There are environmental and technical tradeoffs. Advanced purification requires energy, and the more thorough the treatment, the higher the power demand. Recharging aquifers with recycled water raises concerns that changes in water chemistry could mobilize heavy metals or other contaminants in soils, creating new risks for health and ecosystems. As Ruyle warns, solving one problem should not create another down the road.
Wastewater recycling is not a universal fix, but as climate change reduces other options it is an increasingly attractive and practical tool. For many communities, treated wastewater can stretch existing supplies and reduce reliance on more costly or less sustainable alternatives.