Depressurization, another important cause of contamination, occurs when firefighting efforts remove large amounts of water from the system in a short period of time. “A water line connected to a house can typically drain about 9 gallons per minute,” says Wilton. Firefighters can pump 500 gallons or up to 1,500 gallons of water per minute. So if you were to take five or six pump trucks out of a water line, you’re looking at thousands of gallons of water being extracted from the water system in a very short amount of time.
When this happens, the water pressure drops drastically and the system becomes vulnerable to bacteria or chemicals entering the system from the surrounding environment. Usually, the high pressure of the water inside the system prevents any external contaminants – such as soil or groundwater – from finding their way inside the system components.
Structural damage from fires can also lead to pressure drops, Welton says. In the case of large-scale fires like the Palisades or Eaton fires, you can have large volumes of water uncontrollably drain out of the system due to ruptured pipes and other parts of the system. Where there is damage, smoke and debris can be sucked into the water system, while damaged sewer lines can leak into adjacent drinking water pipes. “When the water company starts to repressurize, they start pushing that contaminated water back into the infrastructure,” Wilton said.
During the 2021 Marshall Fire in Louisville, Colorado, which burned more than 1,000 homes, city officials advised residents to use only mains water for washing until extensive testing confirmed safety. With more than 12,000 structures burned in Los Angeles as of Monday morning, the potential for widespread contamination is significant, Kearns warns.
The coming days and weeks will be decisive. Once water experts assess the damage, they will determine if the system can be cleaned or if infrastructure repairs are necessary. If it’s burned enough, workers have to replace pumps, pipes, and even tanks. For parts of Los Angeles County served by LADWP, McCurry estimates the recovery could take anywhere from a few days to a few weeks.
However, Altadena and surrounding areas are served by several smaller water providers such as Lincoln Water Company, Las Flores Water Company, Rubio Cannon Land and Water Association, and the Kinloa Irrigation District, all of which have issued Do Not Drink Notices. “In the case of a large water system like LADWP, you’re probably going to see things pick up a little faster,” Kearns said. “For smaller water suppliers, who can sometimes only have a few employees and don’t have the budget for these types of events, it can be difficult.” Santa Cruz experienced similar challenges during the 2020 CZU Lightning Complex fire, with water service taking months to stabilize. McCurry warns that some areas may need years to build from scratch or repair large burned systems.
It’s important for residents to stay informed of recovery efforts, Kerns says, because warning systems can be complicated and many residents may not even receive them. He advises that people should “actively seek boil or do not drink warnings from your water supplier, city and county.” “Share them with your neighbors and make sure people who may have a language other than English as a first language get these alerts and understand what’s going on.”
Some places, such as Louisville in Colorado and Maui in Hawaii, released public access maps that tracked water quality per plot of land, which helped inform residents in the months and years that followed.
Before the advisory was lifted, the state of California was legally required to monitor 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 all potential exposures. “It’s possible that some of these chemicals will be around longer than water suppliers expect,” McCurry says. He still advises to be careful. Activated carbon filters can help remove some organic pollutants, but may not completely eliminate the hazards.
“Healthy water can Wilton says to rebuild after the fire. Communities that recover faster and stronger are those that work together and support each other.”
