As firefighters scrambled to extinguish the wildfires consuming neighborhoods across Los Angeles County this month, they often found that the hydrants outside the burning houses were not much help.

It was hardly the first time in recent years that a wildfire had encroached on an American neighborhood, and hardly the first time that hydrants were unable to make a serious dent in stopping an unfolding disaster. In Colorado, Hawaii and other parts of California, hydrants have provided minimal relief as home after home has burned.

A combination of extreme conditions, poor planning and delayed evacuations contributed to the widespread devastation around Los Angeles. There were also specific limitations on the region’s network of fire hydrants, including a large reservoir that was offline for maintenance.

But in most cases, experts say, a working hydrant system would be inadequate for fighting a large-scale wildfire.

While hydrants can provide a valuable first line of defense in the early stages of a wildfire, they can quickly run dry when those fires burn out of control, and especially when wind gusts carry embers across a city.

How Hydrant Systems Work

Fire hydrants have been a staple in American neighborhoods for well over a century, usually fed by city or county water systems.

Many systems use the force of gravity to create water pressure. But they can also rely on electricity, leaving them vulnerable during disasters.

The landscape of a city can determine what its water system looks like.

Hydrants Weren’t Designed for Wildfires

Above-ground fire hydrants have been around since the 1800s. Before fire hydrants became common, firefighters often had to dig into the ground to reach wooden water mains to get water into their hoses.

When the blaze was out, firefighters would then repair the water main with a “fire plug.”

Hydrants make that process far more efficient, though their primary purpose has always been to help extinguish structure fires before they spread across the neighborhood.

But in recent decades, as climate change has made destructive fires more common, and Americans have built more homes in forested areas, hydrants have played a role in controlling brush fires in their early stages.

Still, the systems can be quickly overwhelmed.

After the Woolsey fire in Southern California in 2018, a review found that high demand for water, along with broken pipes in burned structures, led to some neighborhoods having insufficient water pressure, or none at all.

When water ran low during the Marshall fire in Colorado, which ignited in late 2021, officials rushed untreated lake water through the system to keep supplies up, researchers found.

And after the fire on Maui in 2023, officials wrote that it was unclear if the hydrants ran dry because of demand or the loss of electricity.

When Hydrants Aren’t Enough

In large-scale fires, hydrant systems can quickly be pushed beyond what they were engineered to handle. There are multiple ways the systems can fall behind before water even reaches the hydrant.

“Even with water everywhere, what we observed in L.A. I don’t think would have been thwarted in any meaningful way,” said Alan Murray, a geography professor at the University of California, Santa Barbara, who has researched hydrant spacing in fire-prone areas.

Dr. Murray said there were ways to limit neighborhoods’ risk against wildfires, including by creating “defensible space” around homes and limiting fuel sources like wooden fences. Forest management strategies, like prescribed burns, can also help.

But is there a way to build a bigger, better fire hydrant system that can spare neighborhoods from the sorts of wind-driven fires that have burned thousands of homes?

Not likely, experts said.

“The laws of physics and hydraulics are what they are,” said Rob Sowby, an engineering professor at Brigham Young University who studied the aftermath of the Maui wildfire. “We can make bigger reservoirs and bigger pipes and more fire hydrants, but I think it’s going to have to be more of a social and policy decision about where and how we build in the future, and what kind of other protections we make against wildfires.”