By San Diego Mayor Jerry Sanders
December 19, 2011

This past summer, San Diego launched a one-year test of advanced water purification treatment on recycled water. Located in northern San Diego, the Advanced Water Purification (AWP) Facility is a small'scale testing ground that purifies one million gallons of recycled water every day to a level similar to distilled water quality.

The facility is one component of the city's Water Purification Demonstration Project that is examining the safety and cost of purifying recycled water. If this project is approved to go full'scale, the purified water would blend with the city's imported supplies at San Vicente Reservoir and would become part of the city's future drinking water supply. Another component of the Demonstration Project is the study of San Vicente Reservoir and the potential effects of adding purified water to it. During the test phase, purified water will not be sent to the reservoir or the city's drinking water system; instead, the purified water will be added to the city's existing recycled water system.

San Diego is examining water purification as a means to develop a locally controlled, drought-proof, supplemental water supply. San Diego is a semi-arid region in which the annual average of rainfall makes up only about ten to 15 percent of the city's water supply. As such, 85 percent of the local drinking supply on average is imported from hundreds of miles away.

Our city has been both creative and aggressive in trying to diversify our water supply. The less we rely on importing water from outside San Diego County, the more we control our own destiny. A locally produced supply of water could be an important option for us.

All wastewater in San Diego undergoes treatment to remove harmful contaminants, making it safe enough to be discharged into the ocean. Some wastewater is diverted to the city's recycled water facilities, where it is further treated and then used for irrigation and industrial purposes. A portion of the recycled water produced at the North City Water Reclamation Plant is sent to the Advanced Water Purification Facility.

To arrive at a pristine state, the recycled water undergoes the multi-barrier purification process, which includes membrane filtration, reverse osmosis, and advanced oxidation with ultraviolet disinfection and high'strength hydrogen peroxide. The multi-barrier approach of consecutive treatment steps work together to remove or destroy all unwanted materials in the water and produces one of the purest supplies of water available anywhere. Each step in the process also includes continuous water quality monitoring. The city thoroughly examines the safety of the water through laboratory tests and computer analysis to ensure it meets public health standards.

Following the year-long collection of scientific data, the results will determine the safety and cost of a full'scale water purification and reservoir augmentation project. After the test phase is complete, the decision whether to implement a full'scale project will be left to the policy makers.

Recognizing that public acceptance is key to successful water purification implementation, the city's Public Utilities Department has implemented an outreach strategy that encourages public involvement and fosters active dialogue. One of the elements of the outreach program is encouraging visitors to tour the Advanced Water Purification Facility. Guests who participate in the tour gain a better understanding of the Demonstration Project and what role the facility plays in this testing phase. Following an introductory presentation, tour participants walk through the facility to view the water purification technology equipment up close. At the end of the tour, guests view the purified water produced at the facility and have a chance to visually compare it to drinking water and recycled water samples.

Since the Advanced Water Purification Facility opened in summer 2011, city staff has hosted more than 100 tours for approximately 1,400 people. Residents from throughout the San Diego region have visited, bringing along their family, friends and co-workers. Various groups from graduate school classes to the Audubon Society to senior citizen organizations to a fifth grade science class have toured the facility. It's not just local residents who visit, though. Because many countries around the globe are interested in water purification technology as a potential solution to water supply issues, international visitors have come from Mexico, Vietnam, Australia, the United Kingdom, and a number of Eurasian countries.

For more information about San Diego's Water Purification Demonstration Project, visit the website www.purewatersd.org, send e-mail to purewatersd@sandiego.gov, follow us on Twitter @PureWaterSD, like us on Facebook at www.facebook.com/SanDiegoWPDP, or call 619-533-7572. For those interested in touring the facility, visit the website www.purewatersd.org/tours.shtml.