Djakhangir Zakhidov for The Texas TribuneWastewater being treated at a plant in Fort Worth. While its reuse in industry and on golf courses is common, scientists say that recycling will also be crucial to the drinking supply someday.
Each day, American municipalities discharge treated wastewater back into natural sources at a rate that would fill an empty Lake Champlain within six months. Growing pressure on water supplies and calls for updating the ancient subterranean piping infrastructure have brought new scrutiny to this step in the treatment process, which is labeled wasteful and unnecessary by a spectrum of voices.
“As the world enters the 21st century, the human community finds itself searching for new paradigms for water supply and management,” says a report released this month by the Water Science and Technology Board of the National Research Council, a division of the National Academy of Sciences. The report investigates the potential for establishing a more resilient national water supply through the direct recycling of municipal wastewater.
“Law and practice have always been that water goes back into a river or into groundwater or the ocean before it returns for further treatment,” said Brent Haddad, founder and director of the Center for Integrated Water Research at the University of California, Santa Cruz, and a member of the committee that wrote the report. The critical question, he said,
is “whether that natural stage of treatment is actually an efficient stage of treatment.”
Sixteen experts representing industry, government, and research fields in the social sciences and hard sciences collaborated over three years to produce the study, examining everything
from pathogenic risks to public attitudes about reuse.
The committee ultimately concluded that the reuse of municipal wastewater can safely and significantly increase the nation’s available water resources – potable and nonpotable – without intermediate discharge into the natural environment. “The technology for treating wastewater is good enough that we don’t need that intervention,” Dr. Haddad said.
The non-potable reuse of wastewater is not a new idea, especially where water is a historically stressed resource. For decades, the Southwest Florida Water Management District has used recycled wastewater in industry, agriculture and commerce. Ten percent of total water use district-wide now comes from recycling.
By contrast, less than three-tenths of 1 percent of total water use across the United States involves recycling.
Despite Florida’s national leadership in water reuse, not one drop is ever poured from a pitcher or sipped from a glass; it is instead used to keep lawns and golf courses green or to cool industrial machinery and drive steam turbines. A stigma tilts against the idea of drinking recycled wastewater, though experts say that this is largely unwarranted.
“The fact is, people already drink reused water,” said Ken Herd, the water supply program director for the southwest Florida district. In a process known as “de facto reuse,” municipal water facilities are commonly sited on rivers or reservoirs downstream from other wastewater treatment facilities, which leads to a progression of unplanned and unregulated water reuse, from one plant down to the next.
The report found that levels of chemicals in existing water supplies and recycled water are essentially equivalent. Pathogen levels were also equivalent, and sometimes even lower, in recycled water, it said.
“Nonetheless, when reuse becomes the primary intention of water management, this tends to create public pause,” Mr. Herd said.
Legal and regulatory hurdles to widespread wastewater reuse persist. The report notes that wastewater plants that make discharges into ocean and estuaries, like many in Florida, are most suitable for recycling retrofits; high recycling rates along inland rivers could inhibit stream flow and raise legal questions over access rights for downstream users. Of the 32 billion gallons of wastewater discharged every day, 12 billion gallons is discharged into oceans and estuaries.
Regulation of water reuse programs could prove a contentious issue. State- or district-level programs could be upset or overturned if a federal agency were charged with setting public or environmental health guidelines, for example.
“Many state and local officials are leery of a new national standard, either written or implemented as one size fits all,” said Ben Grumbles, the president of the Clean Water America Alliance and a member of the Water Science and Technology Board.
The costs and benefits of water reuse depend on context, he argues, and federal mandates could prove unnecessarily costly in many areas. “That’s why so many people believe that water issues are always local,” he said.
It is not clear whether the federal Environmental Protection Agency has the authority to impose national water reuse standards, because this kind of water management falls into a gray area between the Clean Water Act and the Safe Drinking Water Act.
Despite these challenges, Mr. Grumbles asserts, “the future of water is the reuse movement.” The nation’s swelling population and increasing urban density are driving up demand as climate change slowly destabilizes the supply, he noted.
Desalination and long-distance imports are energy-intensive and costly. Aquifers are being overdrawn, and most dammable rivers are already at the limits of exploitability, he added. “All of this puts a premium on water reuse,” Mr. Grumbles said.
Though reuse is not a silver bullet – such efforts must be accompanied by less costly conservation and efficiency programs – recycled water will inevitably become a “very important part of our national water management portfolio,” Mr. Herd predicts.
Mr. Grumbles agrees. “In essence, there is no wastewater,” he said. “Just wasted water.”