An April 22 Sustainable City Network article reported on the efforts of the Padre Dam Municipal Water District, located in San Diego’s east county in California, to recycle wastewater into drinkable water.  If fully implemented, the water recycling facility could increase the region’s practical water supply by 20 percent. The article explored the technical process used by the Water District in building and purifying wastewater:

The Padre Dam Advanced Water Purification Demonstration Facility in Santee, Calif., is expected to produce approximately 100,000 gallons of purified water every day, but it won’t be put into the drinking water system just yet.

“The demonstration facility is treating water to prove to California regulators that Padre Dam has the ability to produce and treat this kind of water,” said Melissa McChesney, the dam’s communications officer, adding that the facility will do this using a four-step process that includes free chlorine disinfection, membrane filtration, reverse osmosis and advanced oxidation.

The fourth step should give the facility additional credits for removing more constituents from the water, with the goal of shortening the environmental buffer time – or the amount of time the treated water needs to sit in the Padre Dam aquifer before being reused as potable water.

The article also noted the importance of public outreach for such a project:

“This is just as much an engineering project as it is a communication project,” said Albert Lau, Padre Dam director of Engineering. “We have to communicate to the general public about the technology and about the benefit of reusing that water. Once we explain to them and educate them about the process, they get excited about it.”

While the Padre Dam Demonstration Facility is in response to California’s ongoing severe droughts and water-poor desert location of Santee, such facilities are likely to become increasingly common throughout the United States as other states, including Maryland, begin to stress or fully allocate existing water supplies.

As other regions of the United States continue to struggle with drought conditions, Lau said projects like the one at Padre Dam will likely become more common. …

“I suspect we’ll probably get more interest from folks out of state,” he said, adding that tours of the demonstration facility are filling up quickly.

The prospect of being able to both conserve water and provide a more reliable supply are two of the most exciting aspects of the new project, McChesney added.

“We’ve never had an opportunity to provide a local water supply for our customers, and to be able to provide that reliability is fantastic,” she said.