San Diego communities are working together to diversify their water supply, with a plan to convert the wastewater that goes down drains and toilets, into purified drinking water.
The Padre Dam Municipal Water District in Santee is leading the East County Advanced Water Purification Program.
The district is working with Helix Water District, the city of El Cajon, and the County of San Diego to build a full-scale water purification facility on-site at Fanita Parkway.
The goal is to supply about 30 percent of the drinking water in East County by 2023.
A small demonstration facility at the Padre Dam Municipal Water District showcases the four-step process to turn recycled water into purified drinking water.
The first step is free chlorine.
"Through this process we can get 99.99 percent disinfection of virus in a matter of minutes," said Al Lau, Director of Engineering for the Padre Dam Municipal Water District.
The water is filtered even further during the next three steps: membrane filtration, reverse osmosis, advanced oxidation.
Lau said by the end of the process, the water is at near-distilled quality. "It's cleaner than what we're importing from Northern California and the Colorado River right now."
"Water coming from the sky gets to the ground, moves toward the river system, and picks up other contaminants along the way," Lau added. "So by the time we get our water here in San Diego, we're near the end of the pipeline, so that water is not as pristine as we think it is."
Padre Dam Municipal Water District purchases all of its drinking water from the San Diego County Water Authority.
The district converts nearly half of its wastewater into recycled water at its on-site plant.
About two million gallons a day are recycled during the five-step process.
That recycled water is then used to fill Santee Lakes and irrigate public areas.
The rest of it is stored in ponds maintained by the water district.
The other half of the wastewater that isn't recycled, about 2.5 million gallons a day, is sent to the water treatment plant in Point Loma, then discharged into the ocean.
"We view that as a resource that we can hopefully recover to generate a water supply for San Diego, in particular, East County," explained Lau.
Brian Olney, Director of Water Quality and System Operations at the Helix Water District in La Mesa, said the East County Advanced Water Purification Program would provide a new source of water for Helix customers.
Olney said the current agreement between the four entities is a commitment to making sure the project works and developing a better cost estimate.
"That's what this next year and a half is going to look at," said Olney. "What is the cost of the water to customers, and how will the program work between the partners."
The City of San Diego is also developing a pure water program. Construction on its full-scale purification facilities will begin in late 2018.