Last summer, the city opened its doors to a facility that is testing whether it can provide a new, local source of water for San Diego. Located in northern San Diego, the Advanced Water Purification (AWP) Facility is a small-scale, state-of-the-art facility 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 examining the safety and cost of purifying recycled water. If the project is approved to go full-scale, the purified water would be blended with imported supplies at San Vicente Reservoir and become part of the city’s drinking water supply. Throughout the test phase, purified water is not sent to San Vicente Reservoir or the city’s drinking water system. Instead, it is added to the city’s existing recycled-water system. San Diego is examining water purification as a means to develop a locally controlled, supplemental water supply. San Diego’s semi-arid region is at the end of pipelines that bring imported water from hundreds of miles away. The city needs to develop local, reliable water sources to lessen its dependence on expensive and limited imported water supplies.  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 AWP facility.  To become purified water, the recycled water undergoes a 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 removes or destroys all unwanted materials in the water and produces one of the purest supplies of water available.  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 that it meets drinking water-quality standards.  The results of the project’s data collection will determine the safety and cost of a full-scale water purification and reservoir augmentation project. After the test phase is complete, the mayor and City Council will decide on implementing a full-scale project.  The same water purification process is already used around the world from Singapore to Belgium to Australia. Just north of San Diego, Orange County operates the world’s largest water purification plant. The Orange County Groundwater Replenishment System produces up to 70 million gallons a day of ultra-clean water for nearly 600,000 residents and for many businesses and attractions, including Disneyland. The purified water is injected into the county’s drinking water aquifer. This facility is being expanded to produce an additional 30 million gallons a day.  Visitors are encouraged to tour the facility. Guests gain a better understanding of the demonstration project and what role the AWP facility plays in the 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. Register for a tour at www.purewa-tersd.org/tours.shtml. A virtual tour of the AWP Facility is also available at www.purewatersd.org. To request a presentation for an organization, email [email protected], or call (619) 533-6638. For more information about the project, visit www.purewatersd.org, email [email protected], or call (619) 533-7572. — Marsi A. Steirer is the water purification demonstration project director for the city’s Public Utilities Department.