San Diego is moving forward on a project to convert wastewater into drinking water in coming years, according to a plan approved unanimously Wednesday by the City Council’s Natural Resources and Culture Committee.
The plan, due in 90 days, would develop a timeline for building a water-purification system and spell out the next steps. The report would include an analysis of costs, details on how those expenses would be split between water and wastewater agencies, and a description of how the infrastructure would be built.
Five years ago, the city embarked on an $11.8 million demonstration project to see if it could treat wastewater to drinking level standards. The system involves micro-filtration and ultra-filtration, followed by reverse osmosis, ultraviolet light and a hydrogen peroxide treatment.
After 9,000 water-quality lab tests, the demonstration project found that the purified water met all federal and state standards for drinking water. In fact, the treated water contained fewer organic contaminants and dissolved salts than either aqueduct water or drinking water, according to a city staff report.
The next stage would be to build an approximately $370 million facility that could produce up to 15 million gallons per day of treated water, which would supply about 8 percent of the city’s water use. That water would be piped into San Vicente Reservoir, where it would be treated again before being distributed to water users.
The council committee also directed staff to look at options for piping the purified water directly to consumers.
The total cost of purified water would likely be about $2,000 per acre-foot — the amount needed to cover an acre a foot deep, city documents stated. That’s more expensive than water purchased from the Metropolitan Water District, which costs about $1,000 per acre-foot.
But by diverting water from its wastewater system, the purification plant could lead to savings that would bring the net cost to about $1,000 per acre-foot.
DEBORAH SULLIVAN BRENNAN • U-T