LOS ANGELES (AP) — The U.S. can safely increase its drinking water supply by reusing some of the 12 billion gallons of wastewater that pours down sewers and into the ocean each day, a panel of experts concludes in a new report.
The health risks from using reclaimed wastewater in aquifers is the same or even lower than from using existing drinking water supplies that already contain a small percentage of treated sewage, according to the report released Tuesday by the National Research Council.
Derided by critics as "toilet to tap" water, treated wastewater could play a growing role in expanding drinking supplies in areas with surging populations, especially in the parched Southwest.
Many cities already use some treated wastewater in drinking supplies. Las Vegas, for example, sends treated sewage into Lake Mead, which supplies Southern California and other regions.
"Of the 32 billion gallons of municipal wastewater discharged nationwide each day, approximately 12 billion gallons are discharged to an ocean or estuary — an amount equivalent to 6 percent of total water use in the United States," a report summary said.
A committee of experts assembled by the research council looked at the risk of exposure to disease-causing microbes and to 24 chemical contaminants, including pharmaceuticals and hormones.
"Although there is a great degree of uncertainty, the committee's analysis suggests the risk from potable reuse does not appear to be any higher and may be orders of magnitude lower, than currently experienced in at least some current (and approved) drinking water treatment systems," the report stated.
The cost of using treated wastewater for drinking generally tend to be more expensive than expanding water supplies through conservation measures but cheaper than desalinating seawater, the study said.
"Wastewater is a drought-proof supply. People are always generating wastewater," Jorg Drewes, a water reuse expert who was on the committee, told the Los Angeles Times (http://lat.ms/y6992K). "That can be a very viable option, the committee felt, compared to imported water and other options."
The report is encouraging and "underscores the importance of using recycled water to augment existing water resources," Los Angeles Department of Water and Power Assistant General Manager James McDaniel said.
Despite previous opposition, the DWP is trying to build support for a plan to use treated sewage to replenish a groundwater aquifer in the northeastern San Fernando Valley and also is developing a master plan to using recycled water in the city, the Times reported.
The study was sponsored by several federal agencies, and various water and sanitation districts in Southern California and Monterey.