emeritus of Resource Economics at the University of California at Riverside. "Once it's gone through three stages of treatment, the water that ultimately goes out of there is cleaner than they got and flushed away."

California law allows treated wastewater to be used for indirect potable reuse, such as sending the purified water into groundwater basins for capture later as a source of drinking water. A state bill passed in 2013 requires that California's water regulators create a framework for direct potable reuse by the end of 2016.

"While it appears to be likely that the science and available technology will support a positive recommendation to move forward with authorizing DPR (direct potable reuse) through regulations, there is no assurance at this time," according to Richard Mills, chief of theand collected urine.

In 2014, two Texas towns launched the nation's first direct-to-potable reuse water programs. Wichita Falls and Big Spring, about 230 miles apart, treat wastewater with a multistep cleaning process and then send the purified water directly to homes. The last U.S. Drought Monitor data shows 49 percent of Texas suffering from some level of drought.

"The projects in Texas are a proving ground," said Zachary Dorsey, a spokesman for the WateReuse Association. "Throughout the Southwest, people are starting to look more and more at local reuse."

Recycled water

According to Dorsey, it's not unusual for communities in the U.S., including San Diego, to get their drinking water from essentially recycled water in big rivers such as the Colorado River, where by the time it reaches downstream there can be