This presentation discusses a state-of-the-art project to reclaim wastewater effluent currently discharged to the Pacific Ocean for groundwater replenishment in Orange County California. The project will include microfiltration, reverse osmosis and ultraviolet (UV) disinfection for treatment, and pumping and distribution of the product water for aquifer replenishment and saltwater intrusion barrier injection. The evaluation and selection of UV disinfection equipment for the project are discussed below. The project will reduce the Orange County's dependency on imported water supplies in the future, and result in increased efficiency in water use and reclamation in water-short Southern California.