Recycled wastewater is not only as safe to drink as conventional potable water, it may even be less toxic than many sources of water we already drink daily, Stanford University engineers have discovered.

"We expected that potable reuse waters would be cleaner, in some cases, than conventional drinking water due to the fact that much more extensive treatment is conducted for them," said Stanford professor William Mitch, senior author of an Oct. 27 study in Nature Sustainabilitycomparing conventional drinking water samples to wastewater purified as a drinking water, also known as potable reuse water.

"But we were surprised that in some cases the quality of the reuse water, particularly the reverse-osmosis-treated waters, was comparable to groundwater, which is traditionally considered the highest quality water."

As drinking water sources become more scarce, the discovery is promising news for a thirsty public and utility companies struggling to keep up with demand.