During its July 2 meeting, the Bird Rock Community Council (BRCC) heard a presentation on the city’s plan to purify waste water from homes and businesses for human consumption — a project commonly (and derisively) referred to as toilet-to-tap.
Peter Martin, a senior water resources specialist with the San Diego Public Utilities Department, discussed the project, which involves building a reclamation plant and related infrastructure that the city estimates will cost about $369 million.
Though there was much backlash to the proposal when the city first proposed it a decade ago, Martin said a nearly identical system has been used successfully for the past five years in Orange County, and public support for recycled waste water is slowly growing statewide.
Last summer, San Diego completed a one-year test of its proposed waste water reclamation system at the city’s Water Purification Demonstration Project plant near UTC.
The demonstration plant produced about 1 million gallons of recycled waste water per day during the trial, which was tested before being put back into the regular recycling system for use in irrigation and industry.
Martin said results of the one-year waste water recycling demonstration found that the “overall water quality was exceptional,” “very similar to distilled water” and “met all the drinking water standards required by the state permitting authorities.”
The proposal involves construction of an Advanced Water Purification Facility where normally treated waste water would undergo additional membrane filtration, UV radiation and reverse osmosis, as it did during the demonstration phase.
Martin said the water is tested between each filtration step to assure each process is working as intended.
The project would provide about 8 to 10 percent of the city’s water supply — or about 15 million gallons per day during the first phase, he said (a report by the Equinox Center estimates the project could eventually produce as much as 40 percent of the city’s water supply).
Factoring in water treated at the proposed Carlsbad desalination plant (which Martin said would provide about 7 percent of the region’s water supply), such alternative water purification projects would significantly reduce the region’s reliance on water imported from Northern California (the cost of which Martin said has doubled in the past decade, and will likely double again in the next 10 years).
“That has a lot to do with aging infrastructure … (as well as) the increasing cost of energy (required) to pump that water down to Southern California,” he said. “The deltas and levies up in Northern California need a lot of repair.”
Martin said the city council is still grappling with how to fund the project, which will cost about $2,000 per acre-foot of water, or a little less than the Carlsbad desalination project (about $2,300 per acre foot).
However, officials estimate the project would eventually save taxpayers $1 billion by eliminating required upgrades to the Point Loma waste water plant.