The second major contributor to contamination, depressurization, occurs when firefighting efforts draw large amounts of water from the system in a short period of time. “A water line connecting to a house can typically draw about 9 gallons of water per minute,” says Whelton. Firefighters can draw up to 500 gallons or 1,500 gallons of water per minute. So if you run five or six pumper trucks off a water line, you're looking at thousands of gallons of water being removed from the water system in a very short period of time.
When this happens, the water pressure decreases, and the system becomes vulnerable to bacteria or chemicals entering the system from the surrounding environment. Typically, the high water pressure inside the system prevents any external contaminants – such as soil or groundwater – from finding their way inside the system's components.
Whelton says the pressure loss could also be due to structural damage from the fire. In the case of large-scale fires such as the Palisades or Eaton fires, large amounts of water can escape uncontrolled from the system due to rupture of pipes and other parts of the system. Where damage occurs, smoke and debris can enter the water system, while damaged sewage lines can leak into drinking water pipes flowing nearby. “When the water system starts trying to apply utility pressure, they start pushing that contaminated water through the infrastructure again,” Whelton says.
During the Marshall Fire in Louisville, Colorado in 2021, which burned more than 1,000 homes, city officials advised residents to only use main water for flushing until extensive testing confirmed safety . Given that more than 12,000 structures had burned in Los Angeles as of Monday morning, the potential for widespread contamination is significant, Kearns warned.
The coming days and weeks will be important. Once water experts assess the damage, they will determine whether the system can be cleaned or whether infrastructure repairs are necessary. If much has burned, workers will need to replace pumps, pipes and even tanks. For parts of Los Angeles County served by LADWP, McCurry estimates this recovery could take a few days to weeks.
However, Altadena and the surrounding areas are served by several smaller water providers. Lincoln Avenue Water Company, Las Flores Water Company, Rubio Canon Land and Water AssociationAnd Kineloa Irrigation District-All of whom have issued a notice not to drink alcohol. “In the case of a larger water system like LADWP, you'll probably see things reopen a little faster,” Kearns says. “For smaller water providers, who sometimes only have a few employees and don't have the budget for these types of events, they may struggle some.” Santa Cruz faced similar challenges during the CZU Lightning Complex Fire in 2020, which took several months to stabilize water service. McCurry warned that it could take years for some areas to rebuild or repair large systems that have burned.
Kearns says it's important for residents to stay informed about recovery efforts, as alert systems can be complex, and many residents may not even receive them. “People should actively look for any boil or do not drink water alerts from their water provider, their city, their county,” she advises. “Share them with your neighbors and make sure people who have languages other than English as a first language receive the alerts and understand what's happening.”
Some places, such as Louisville in Colorado and Maui in Hawaii, released public access maps that tracked water quality on each land plot, helping to keep residents informed during the coming months and years.
Before lifting the advisory, water providers are legally required by the State of California to monitor for benzene. However, Whelton cautions that benzene is not the only chemical of concern and the list of potential contaminants is long. Government and third-party testing services do not always account for every potential risk. “It's possible that some of those chemicals may persist longer than water providers expect,” McCurry says. He still advises to remain cautious. Activated charcoal filters can help remove some organic contaminants, but they cannot completely eliminate the risks.
“Safe water can do Can be restored after a fire,'' says Whelton. “The communities that heal faster and are stronger are those that work together and support each other.”