The city of Antioch has opened its new brackish water desalination plant, a $116 million facility designed to improve the reliability of local drinking water supplies by treating water from the San Joaquin River.
The project was celebrated in a ceremony attended by representatives from the State Water Resources Control Board, the Department of Water Resources (DWR), the Contra Costa Water District, the city of Brentwood, and other local and state officials.
The plant can produce up to 6 million gallons of drinking water per day by removing salt from brackish river water. It features a microfiltration/ultrafiltration system for pre-treatment and a two-stage reverse osmosis system. Depending on water conditions, the facility is expected to supply up to half of Antioch’s water during certain months and about 30% of its annual supply.
The State Water Resources Control Board supported the project with a $60 million low-interest loan from the Drinking Water State Revolving Fund, a state and federal program that finances water quality improvements. The Department of Water Resources also provided a $10 million grant through its Water Desalination Grant Program, funded by Proposition 1.
Depending on water conditions, the facility is expected to supply up to half of Antioch’s water during certain months and about 30% of its annual supply
Antioch currently serves more than 112,000 residents, relying on water from the San Joaquin River and purchases from the Contra Costa Water District. Increasing river salinity in recent years has made the city more dependent on purchased water. The new facility enables Antioch to treat its own brackish water at less than half the energy cost of seawater desalination.
The plant aligns with Governor Gavin Newsom’s Water Supply Strategy, which aims to address an anticipated 10% reduction in California’s water supply by 2040 through increased conservation, storage, recycling, and stormwater capture. The Antioch facility is the eighth brackish desalination plant now operating in the state, out of 14 planned by 2040.
“The Department of Water Resources is proud to support Delta communities in their efforts to adapt to climate change,” said DWR Director Karla Nemeth. “It’s this type of state-local partnership that enables innovative, new technologies to secure water supply over time for communities like Antioch as rising sea levels bring water quality challenges right to their doorstep. We have to move with a sense of urgency, and this project ensures Antioch will have enough water during the next drought, which is typically right around the corner.”
