San Francisco firefighters will now be able to tap into an emergency water supply when battling the city's next major blaze.
More than 150 underground water tanks, called cisterns, have been strategically placed throughout San Francisco.
"They provide standing pots of water in the event of a large-scale emergency," San Francisco Fire Chief Joanne Hayes-White said. "We can tap into that water source and suppress a fire."
Utility officials said the city learned a hard lesson during the 1906 earthquake by relying only on the existing water supply system.
In 2010, voters approved a bond measure that generated $1.4 million to pay for 30 new cistern tanks. Each new tank holds 75,000 gallons of water, officials said.
Voters this June will be asked to vote on Proposition A, which would provide $55 million to build more underground water tanks.
"We're good planners in the fire department. Our history has showed us that there are water mains that can break," Hayes-White said. "We want to be able to have other options in the event of system failures."