A major reservoir in the Pacific Palisades was offline and empty when fires broke out last week, reports the Los Angeles Times.
The Santa Ynez Reservoir, which typically holds 117 million gallons of water, was closed for repairs to its cover, according to the report.
Los Angeles firefighters ran out of water when fighting the fires, which Department of Water and Power officials blamed on demand during an unprecedented situation.
The wildfires have killed at least 10 people and destroyed thousands of structures.
Former DWP general manager Martin Adams, an expert on the city's water system, told the Times the water in the Santa Ynez Reservoir would have helped, but "you still would have ended up with serious drops in pressure."
"Would Santa Ynez [Reservoir] have helped? Yes, to some extent. Would it have saved the day? I don't think so."
Los Angeles City Council member Traci Park, whose district includes Pacific Palisades, said the city's water systems were among several pieces of critically underfunded infrastructure.
"There are environmental catastrophes waiting to happen everywhere with our water mains," she told the New York Times, adding that some were a century old.
"As our city has grown, we haven't upgraded and expanded the infrastructure that we need to support it."
The two biggest fires devastating the Los Angeles area grew just slightly as firefighters began Friday to gain some control of blazes that obliterated neighborhoods and left the nation's second-largest city on edge.
The level of devastation is jarring even in a state that has grown used to massive wildfires. Dozens of blocks of scenic Pacific Palisades were flattened to smoldering rubble. In neighboring Malibu, oceanfront homes next to a fire station were in ruins.
Information from The Associated Press was used in this report.