Update on city’s water purification project presented to Carmel Valley planning board


By Karen Billing

The Carmel Valley Community Planning Board heard an update June 27 on the city’s Water Purification Demonstration Project, which has proved that purified water can be produced and safely added to the San Vicente Reservoir.

San Diego City Council commissioned the purification project to study the feasibility of turning recycled water into purified water for drinking as concerns rise about the future challenges of the city’s limited water supplies.

“It would be a landmark development for indirect potable reuse,” said Cathy Pieroni, senior water resources specialist at the city’s public utilities department.

At its latest stage, the water purification facility could generate 90 million gallons to San Vicente, representing 40 percent of the city’s water supply.

The findings from the demonstration project’s report were adopted by City Council in April and staff was given 90 days to provide additional information and do community outreach. To that end, Pieroni has been touring the city, visiting local planning groups, like Carmel Valley’s, giving presentations. It is expected back before the council in the next month for the public utilities department to present a formal recommendation on the water purification facility.

Pieroni said local water solutions are at a premium as San Diego relies on importing nearly 90 percent of its water from sources in Northern California and the Colorado River. Importing water is expensive and the reliability of deliveries can be impacted by issues such as drought and pumping restrictions, like those that resulted from the protection of the Delta smelt fish in Northern California.

During the year-long test, the Water Purification Demonstration Project facility in UTC produced one million gallons of purified water a day.

The process works by taking recycled water from the North City Water Reclamation Plant and taking it through a multi-barrier water purification process that includes membrane filtration, reverse osmosis and UV/advanced oxidation. The water undergoes frequent monitoring and safeguards are built in to ensure public health will never be compromised. Since 2008, Orange County’s Groundwater Replenishment System has used this process to provide purified water for that region.

The project study concluded that the facility produces good quality water that meets all state and federal standards. The energy use required for purified water is comparable to imported water and the cost of local water would be less, Pieroni said.

Pieroni said the purified water from the facility would cost $2,000 per acre foot of water. Imported water now comes with a price tag of $2,000 per acre foot, and is expected to double in the next decade.

The Water Purification Demonstration Project facility is open for public tours. For more information on the project or tours, visit purewatersd.org or call (619) 533-7572.