Jun 14, 2022

By replacing chlorine as the main disinfectant, the quality of the outgoing water is enhanced.

Thanks to recent upgrades made to the Patterson Pass Water Treatment Plant in Livermore, residents in the Tri-Valley region will notice a significant improvement in the taste and quality of their tap water.

Last Thursday, the Zone 7 Water Agency hosted a ribbon-cutting ceremony to mark the unveiling of the recently renovated plant, which required an investment of $110 million for planning, design, and construction.

Upgrades made to the plant comprised the installation of ozone treatment facilities, replacement of aging equipment, and expansion of treated water storage capacity through the installation of a new tank with a capacity of five million gallons. These enhancements will enable the plant to double its treated water production capacity from 12 million gallons per day to 24 million gallons per day, as stated in a news release by Zone 7.

The project, which had been planned for decades, was approved for construction in 2019 by the Zone 7 Board of Directors and was finally completed in the spring of 2022.

Board President Angela Ramirez Holmes stated in a press release, “Zone 7’s investment in cutting-edge technology demonstrates our unwavering dedication to providing our community with high-quality water. By implementing ozonation, a tried and tested treatment method, we are confident that our water will be purer, safer, and more flavorful for our customers, straight from the tap.”

According to Zone 7, the ozonation project is the most recent effort to enhance the efficiency of the treatment process and upgrade water quality to better benefit the community. The new process will operate by infusing ozone into the water, which will promptly start to oxidize and remove pollutants.

As per Zone 7, the Patterson Pass Water Treatment Plant has been providing services to the agency since 1962, by treating imported surface water from the nearby South Bay Aqueduct through the application of dual-media filtration and chlorine treatment methods.

However, in recent years, this method has become less effective in dealing with high levels of organic matter and more frequent algae blooms, which can cause taste and odor issues. Algae blooms refer to the rapid growth or accumulation of algae in freshwater or marine water systems that can produce harmful toxins.

Zone 7 stated that “the blooms are normal but are becoming more frequent”. After reviewing different treatment methods, the agency chose ozone over chlorine as the primary disinfectant, which will result in better quality water for customers by decreasing chlorine-related byproducts and killing more pathogens than chlorine.

Zone 7 is responsible for supplying water to the entirety of eastern Alameda County, and also sells wholesale treated water to local retailers such as the California Water Service Company, the Dublin San Ramon Services District, and the cities of Livermore and Pleasanton. Additionally, the agency is tasked with flood control in the Amador and Livermore valleys.