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Water

SF's Lifeline in Firefighting: How SFPUC Ensures Reliable Water Supply

Underground, an engineer inspects the interior of an existing cistern on 25th St. and San Bruno Avenue.
  • Sarah Peters

With wildfires becoming an increasing threat across California, emergency preparedness is more important than ever. In San Francisco, our multi-layered water system is designed with built-in redundancies to ensure hydrants remain operational and firefighters have reliable access to water when it’s needed most. In fact, they can even draft saltwater from the Bay if called upon! 

Different fire hydrants throughout the City.

Here’s a breakdown of how the SFPUC support's firefighting efforts and protect residents and businesses: 

  • The Municipal Drinking Water System is San Francisco’s primary water source for firefighting. It supplies approximately 8,500 white fire hydrants across the city, which are an essential resource for routine firefighting operations. Water is stored in 12 reservoirs and six tanks within the City, with additional sources available from the Peninsula, East Bay, and the High Sierra.  
  • The Emergency Firefighting Water System (EFWS) was originally built in response to the devastating 1906 earthquake. Unlike the municipal system, the EFWS can deliver water at much higher pressures – a necessity in combatting large fires. It can also draw on unlimited water from the Bay. The system operates independently of the municipal drinking water system and includes: 
    • 135 miles of high-pressure pipelines delivering water to larger hydrants citywide. (Keep your eyes out for these hydrants – their tops will be colored blue, black, or red; these colors indicate the pressure zone and the reservoir they draw from.) 
    • A high-elevation reservoir, two large-capacity tanks, and two seawater pumping stations capable of drawing water directly from the Bay, ensuring an unlimited firefighting water source. 
    • Bay water intakes and suction connections, allowing firefighters to access water from the waterfront as needed. 

Since taking over management of the EFWS from the SF Fire Department in 2010, the SFPUC has made long-lasting seismic and operational improvements to help prepare San Francisco for multiple-alarm fires, natural disasters and the unpredictable. In partnership with the Fire Department and the Department of Public Works, the SFPUC has made several critical updates including: 

Look for brick circles in San Francisco's intersections, which mark an underground cistern. (This one is outside a fire station in the Mission.)
  • The installation of 30 new cisterns across the city, including 15 in westside neighborhoods, bringing the citywide total to roughly 200 cisterns. Most can hold approximately 75,000 gallons of water each. The largest cistern is located near City Hall and can hold approximately 220,000 gallons – the equivalent to a large swimming pool! 
  • Construction of new pipelines, including one in the Candlestick Point/Carroll Avenue area. 

Next Up: A New Potable Emergency Firefighting Water System on the Westside 

The SFPUC and our City partners are working on a new Potable Emergency Firefighting Water System on the west side of the City. This seismically resilient system will serve drinking water during normal operations but can switch to delivering water at high pressure from our drinking water system or from Lake Merced during emergencies. While portions of the 16-mile pipeline have already been constructed, the majority remains in the planning and design phases, with construction expected through 2040. These upgrades are funded by voter-approved earthquake safety and emergency response bonds.