SAN DIEGO, CA — Located in southern San Diego County, the Otay Water Treatment Plant, with a capacity of 34 million gallons per day provides drinking water to an estimated 100,000 customers. The plant is operated by the City of San Diego and located less than two miles from the United States – Mexico border, north of Tijuana. Despite being 15 miles from the Pacific Ocean, the arid region is considered part of the Colorado Desert and receives an average of only ten inches of rain each year.