Los Angeles wildfires raise another issue – unsafe drinking water

Depressurization occurs when firefighting efforts remove large amounts of water from a system in a short period of time, which is another significant contributor to contamination. “A water pipe connected to a house typically sprays about 9 gallons of water per minute,” Whelton said. “Firefighters can pump 500 gallons or as much as 1,500 gallons of water per minute. So if you're running five or six pump trucks on a water line, you're looking at thousands of pumps being pumped out of the water system in a very short period of time. Gallons of water.”

When this happens, water pressure drops dramatically and the system becomes susceptible to bacteria or chemicals entering the system from the surrounding environment. Typically, high-pressure water within a system prevents any external contaminants, such as soil or groundwater, from getting inside the system components.

Structural damage from a fire can also cause a loss of pressure, Wheelon said. In the event of a large fire like the Palisades or Eaton fires, large amounts of uncontrolled water may be dumped from the system due to rupture of pipes and other parts of the system. Where damaged, smoke and debris can be drawn into the water supply, while damaged sewer lines can leak into nearby drinking water lines. “When water system utilities start trying to repressurize, they start pushing contaminated water into the infrastructure again,” Whelton said.

After the 2021 Marshall Fire in Louisville, Colorado, destroyed more than 1,000 homes, city officials advised residents to only use tap water to flush toilets until extensive testing confirmed it was safe. Kearns warned that with more than 12,000 buildings burned in Los Angeles as of Monday morning, the potential for widespread contamination was high.

The coming days and weeks will be crucial. Once water experts assess the damage, they will determine if the system can be flushed or if infrastructure needs to be repaired. If enough burns, workers will need to replace pumps, pipes and even water tanks. McCurry estimated that recovery could take days to weeks for the parts of Los Angeles County served by LADWP.

However, Altadena and the surrounding areas are served by several smaller water companies, such as Lincoln Avenue Water Company, Las Flores Water Company, Rubio Canon Land and Water Association, and Kiniloa Irrigation District, All these companies have issued notices prohibiting consumption. “For a large water system like LADWP, you might find things come back a little quicker,” Kearns said. “For smaller water providers, who may only have a few employees at times and don’t have the budget to host these types of events, they may have some difficulties.” Santa Cruz also suffered during the 2020 CZU Lightning Complex fire After similar challenges, it took months for water services to stabilize. McCurry warned that it could take years for some districts to build from scratch or overhaul large systems that have burned out.

Kearns said it's critical for residents to stay informed about recovery efforts because alert systems can be complex and many residents may not even receive alerts. She recommended that people should “proactively look for any boil water or don't drink warnings” from their water suppliers, cities, counties. “Share this information with your neighbors to ensure that anyone who may speak a language other than English as a first language can receive these alerts and understand what is happening.”

Some places, like Louisville, Colorado, and Maui, Hawaii, have released public access maps that track water quality in each parcel, which can help keep residents informed in the coming months and years.

California legally requires water suppliers to monitor benzene levels before lifting warnings. However, Whelton warns 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 possible exposures. “Some of these chemicals may remain around longer than water suppliers expect,” McCurry responded. He still advises remaining vigilant. Activated carbon filters can help remove some organic contaminants, but they may not completely eliminate the risk.

“Safe water able Recovery after a fire,” Wheelton said. “Communities that work together and support each other are the ones that recover quickly and emerge stronger. “