Located in southern San Diego County, the Otay Water Treatment Plant, with a capacity of 34 million gallons per day (MGD), 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.

With virtually no local water sources available for use, the City of San Diego relies on water from the Metropolitan Water District, which imports its water from the Colorado River and the California State Water Project. The two massive water projects bring water from other watersheds and regions hundreds of miles to the north and east.

Constructed as a conventional treatment plant, the Otay Water Treatment Plant used chlorine dioxide produced from chlorine gas for disinfection as the incoming water was high in naturally occurring organic matter. While the use of chlorine gas provided a strong disinfectant for the treated water, operators with the City began to consider other disinfection options as the area surrounding Otay grew and expanded. Given the residential encroachment around the plant, the City wanted to find safer alternative sources of chlorine. Senior Water Operations Superintendent, Jim McVeigh was forward-leaning in seeking innovative technologies to provide safer, more sustainable water disinfection for the community.