As crews battled the rapidly spreading fires in the Los Angeles area, they were repeatedly hampered by low water pressure and dry fire hydrants. These problems have exposed vulnerabilities in urban water systems that are not designed to handle wildfires of this magnitude, experts say.

The water system that serves the neighborhoods simply isn’t capable of delivering such large amounts of water over several hours, said Martin Adams, former general manager of the Los Angeles Department of Water and Power.

“The system was never designed to fight a wildfire that then engulfs a community,” Adams said in an interview with The Times.

Limitations on local water systems complicated firefighting in Pacific Palisades, where numerous fire hydrants were running low or no water, and in Altadena and Pasadena, which are served by separate utilities and where firefighters said they were struggling with low water pressure.

The local water system in the Palisades area is designed to deliver enough gallons per minute to fight a house fire or a fire in an apartment or commercial building, Adams said. “Then there’s a massive fire throughout the community and there are 10 times as many fire departments all pulling water out of the system at once.”

When a wildfire breaks out, firefighters in Los Angeles often resort to using aircraft to drop water and fire retardant.

But as the flames spread quickly on Tuesday and Wednesday, officials temporarily grounded water-dropping helicopters because of exceptionally strong Santa Ana winds, making crews more dependent on limited water systems on the ground.

To help, city officials sent tankers to deliver water to crews in areas where supplies were limited.

The firefighting efforts put enormous strain on the area’s water system, “taxing the system to the limit,” according to Janisse Quiñones, DWP’s executive director and chief engineer, with four times the usual water demand for 15 hours. She said the fire hydrants rely on three large water tanks, each holding about 1 million gallons. Fire hydrants worked at lower elevations, but in hillier areas like the Palisades Highlands — where storage tanks contain water that flows by gravity to communities below — they dried up.

The DWP and city leaders have faced criticism from residents as well as Rick Caruso, the project developer and former mayoral candidate “Mismanagement” and old infrastructure were to blame.

But water researchers said infrastructure limitations are a common feature of many urban water systems.

“Local water systems are typically designed to fight local, small fires over a limited period of time,” said Kathryn Sorensen, research director at Arizona State University’s Kyl Center for Water Policy. “They are generally not designed to fight large, long-lasting wildfires.”

The restrictions raise several questions: Should storage tanks and other local water infrastructure be expanded to cope as fires grow larger and more intense in the West? Where? And at what price?

Sorenson said utilities need to consider how much water storage capacity they can develop in suburban areas.

“Given the known risk of wildfires in these hills, it is reasonable to question whether more water storage should have been added in recent years and months,” she said.

Los Angeles’ existing water system has “significant limitations,” said Gregory Pierce, director of the UCLA Water Resources Group. “At least the way we have always built systems and wanted to pay for systems, you can’t really expect systems, even like DWPs, to be prepared for this.”

The extent of the fires has surpassed previous fire disasters in LA. The Palisades Fire grew quickly and has destroyed more than 5,000 homes and other buildingsand the Eaton Fire in Altadena and Pasadena damaged or destroyed an additional 4,000 to 5,000 homes and other buildings.

The causes that started this and other fires are currently under investigation.

The fires broke out after a sharp change from wet weather to extremely dry weather Climate “whiplash” that scientists say the risk of wildfires is increasing. Research has shown that these abrupt fluctuations between humidity and dryness are becoming more frequent and intense due to human-caused climate change. Scientists have found that global warming has contributed significantly to larger and more intense wildfires in the western United States in recent years.

Because city fire hydrants are not designed to handle larger, wind-driven fires, firefighters prepare with emergency plans for situations where they need to provide their own water using tankers, said Arthur Lester, a spokesman for the LA County Fire Department.

DWP, which has sent tankers to help firefighters, said the intensity of the fires thwarted those plans. Utility crews had limited access to the three storage tanks in the Palisades, and in one case, DWP crews who attempted to divert water to refill a tank had to be evacuated, officials said.

DWP has urged all customers, particularly those on the Westside, to conserve water to prioritize supplies for firefighting.

In Altadena, firefighters encountered similar problems with low water pressure as they tried to slow the spread Eaton Fire. Pasadena Fire Chief Chad Augustin said the fact that dozens of fire engines were battling multiple fires led to strain on the water system.

“In addition, we had a temporary power outage” that affected the system, he told reporters Wednesday.

Even if crews had had more water, “we couldn’t stop the fire last night with those gusts of wind,” Augustin said. “These erratic gusts of wind threw the embers several miles in front of the fire, and that was actually the reason the fire spread so quickly.”

He said such water shortages are to be expected if such a large forest fire occurs in an urban area. And on Thursday, Augustin said the days of low water pressure in the hydrants were over and firefighters were no longer having problems.

“It’s very common in a city to have a fire this big with so many resources put a strain on our water supply and water system,” Augustin said. “And if there is a loss of power that can impact pressure, it will make things worse.”

Firefighters began talking over the radio about fire hydrant problems Tuesday evening, just hours after the Eaton fire broke out.

“I’m having some water issues to the east and west and the entire north end of the fire,” a firefighter said over the radio.

“We’re getting water to process it,” a dispatcher replied.

The problems reported by firefighters in parts of Altadena occurred in Districts served by two small suppliersRubio Cañon Land and Water Assn. and Lincoln Avenue Water. Representatives of these suppliers could not be reached for comment.

The Eaton fire broke out in an adjacent area served by the Kinneloa Irrigation District, and the flames caused minor damage to a generator that has since been repaired, said Tom Majich, the district’s general manager.

Despite that damage, the district provided water to firefighters by using backup generators and borrowing water from Pasadena Water and Power, Majich said.

“All of our pumps were operational,” he said. “We pumped water throughout the entire event.”

He said the district’s success in maintaining water flow was due in part to lessons learned from the Kinneloa fire in 1993, when a shortage of generators and power outages deprived firefighters of water. This time, he said, his district has prepared its system for an emergency. However, he added that there are problems in other areas due to infrastructure limitations.

“To fight a wildfire, you have to get past Lake Havasu,” he said. “You could fill a rose bowl with water and there wouldn’t be enough water.”

“There is no system that can do this,” he said.

Topography also plays a role in communities where water is pumped from the valley floor to storage tanks on hills.

Sorensen said any water utility that serves an area with large elevation changes will have similar restrictions. Engineers design water systems with pressure zones in 100-foot increments. A place like Pacific Palisades, for example, rises above sea level to over 1,500 feet.

By comparison, in Phoenix, the city supplies water to a huge area with many hills and mountains and has nearly 80 pressure zones, Sorensen said.

“Phoenix’s largest pressure zone is huge and the storage capacity within it is so great that Phoenix could fight multiple fires over a very long period of time without running out of fire hydrant pressure,” she said. “Other print zones are very small and serve only a few customers, sometimes less than a dozen. Storage in these pressure zones will be much smaller and there likely will not be enough stored water to fight more than a small house fire.”

Although infrastructure investment decisions are often driven by population, the risk of wildfires in hillside areas is another factor that utilities should consider when building water storage infrastructure, Sorensen said. In the Los Angeles area, she said, it would have been very costly to develop additional storage “that would be sufficient to contain or even fight the wildfires in these higher pressure zones, but right now I would imagine that “That’s what most people in Los Angeles would say.” “It was worth it.”

Pierce said there may be opportunities to invest in local infrastructure to expand water capacity for firefighting in Pacific Palisades if area residents are willing to bear the high cost of such investments.

“It will have a high cost,” he said. And he added that such additional water storage might not have been able to stop a fire of this size and intensity anyway.

Pierce pointed out that this type of water problem has occurred in previous fires in Malibu and other areas, where firefighters encountered dry fire hydrants and used swimming pools or drew water from the ocean.

“Whether there’s a short-term future where we could and should do more, and a long-term future where you could think about doing a lot more at incredibly high costs, those things are on the table,” Pierce said.

Adams, the former DWP general manager, said the gap between what the L.A. water system was built for and the dangers of massive, fast-spreading fires is widening.

“The urban interface is changing and we designed for classic fires, not a wildfire sweeping through a community,” Adams said. “We need to think about fire safety and what firefighters really need if this is to be the way of the future.”

Times staff writer Grace Toohey contributed to this report.