Hours before devastating fires scorched the historic town of Lahaina on Maui, Kyle Ellison labored to save his rental house in Kula, a rural mountain town 24 miles away, from a different blaze.

As high winds whipped burning trees and grass, Ellison and his landlord struggled with plummeting water pressure. Ellison had to wait for pots to slowly fill in the sink before running them to the fire; his landlord wielded a garden hose with little more than a trickle. Firefighters had to rush away for half-hour stretches to find a working fire hydrant to refill their tanker, and every time they did, the fire gained.

“It’s a very disconcerting feeling when the fire department shows up and they don’t have water,” Ellison said.

The lack of backup power for critical pumps seriously hindered firefighting in Kula, county water director John Stufflebean told The Associated Press. Once the winds knocked out electricity, pumps were unable to push water up into tanks and reservoirs that were key to maintaining pressure.

“If all those (pumps) had had generators, I think there is a pretty good chance we could have kept up,” Stufflebean said.

Kula’s experience exposed a common vulnerability in the U.S., where many water systems don’t have sufficient backup power to guarantee pressure if fires, storms or cold take electricity offline for long periods. Besides hamstringing firefighting, the lack of pressure can make water systems vulnerable to contamination that jeopardizes clean drinking water.

The impact of August’s fires in Kula was far smaller than in Lahaina, where at least 97 people were killed and some 2,200 buildings destroyed in a fire so hot thousands of water pipes melted. More generators wouldn’t have made a difference there, Stufflebean said. But it might have in Kula, where no one died but a few dozen buildings burned.

Experts say backup power systems are expensive. The Environmental Protection Agency, which enforces clean drinking water standards, recommends but doesn’t require utilities to have backup systems — even as climate change is leading to more frequent and damaging extreme weather events.

“Right now, a robust national study to understand the degree of that vulnerability is what’s needed,” said Alan Roberson, executive director of the Association of State Drinking Water Administrators.

Brief power disruptions are common, and water systems typically rely on water still in the pipes or kept in tanks and reservoirs to temporarily maintain pressure, according to Chad Seidel, president of Corona Environmental Consulting. The problem comes when a catastrophe hits and water quickly leaves through fire hoses or damaged pipes, and there’s no power to keep moving new water in.

The American Water Works Association advises providers to have a plan for up to three days without power. Big cities usually have done some emergency planning, and some states have added requirements in recent years to ensure utilities function at least a while without power.

But much of the responsibility to keep water flowing falls to thousands of local utilities across the country, many with limited funds, said Andrew Whelton, a Purdue University professor who studies drinking water contamination following wildfires.

At Ellison’s rental property in Kula, the flames were finally stopped about 10 feet from his home. But smoke and ash penetrated every surface, and Ellison, his wife and their three sons have had to live in a series of temporary homes since then.