L.A. fires put new drinking-water safety measures to the test

Yahoo

08-03-2025

A month after the 2017 Tubbs fire, a Santa Rosa resident finally returned home to one of the handful of houses still standing amid a field of destruction. They turned on their kitchen faucet and smelled gasoline.
It was an immediate red flag for Santa Rosa Water, which quickly sent over technicians to test the tap. In the water, they found benzene, a known carcinogen — a discovery that sent shockwaves through the scientific and water safety world.
In Santa Rosa, the contamination investigation would expand from a single household to the entire burn area.
As devastating urban wildfires continued to increase in frequency in the American West, the problem would reappear — in Paradise, Calif.; in Colorado; in Hawaii; and finally in L.A.'s Pacific Palisades and Altadena. All the while, scientists, regulators and local utilities raced to figure out what was happening and how to keep residents safe.
By the time the Eaton and Palisades fires broke out, scientists and the state could hand the affected utilities a playbook on how to restore safe water for their customers. The lessons learned helped the Los Angeles Department of Water and Power, which serves the Pacific Palisades, restore safe drinking water to all its customers just two months after the fires erupted — compared to an entire year in Santa Rosa.
Yet, the Altadena utilities are still fighting to restore safe water. And, as with the Tubbs fire, the recovery has still been tinged with persisting scientific debates and uncomfortable unknowns.
'We are in a sort of brave new world as we shift into this reality of increasingly more urban wildfires,' said Edith de Guzman, who researches water equity and climate adaptation policy at UCLA. 'We have impacts that we're not really even sure how to measure or monitor.'
Read more: Inside the battle to restore drinking water in Altadena and Pacific Palisades
Benzene wasn't the only contaminant in Santa Rosa's and L.A.'s postfire water. Scientists are still debating which chemicals utilities ought to test for and which, given the costly and timely process of analyzing for dozens of chemicals, can go unchecked.
And, while scientists have studied the danger of long-term exposure to trace amounts of contaminants like benzene in drinking water, less is known about the short-term risks of high exposures through day-to-day activities like showering and running the dish washer.
After the smoke settled in Altadena and the Pacific Palisades, the local water utilities quickly issued 'do not drink' and 'do not boil' orders, under the advice of the state regulator — the State Water Resources Control Board's Division of Drinking Water.
The orders are designed to limit dangerous exposures to benzene, found in everything from plastic to treated construction wood to wildfire smoke. Over decades, drinking or breathing it in can increase the risk of developing leukemia and other blood cancers.
While boiling water can kill off the typical non-fire contamination suspects, pathogens, it doesn't work for benzene. And, with a lower boiling point than water, benzene can easily enter the air when water is heated up.
Consequently, the state has developed best practices to keep residents safe, including not only avoiding drinking or boiling the water, but also avoiding hot showers, hot tubs and clothes dryers.
However, scientists warn that these recommendations are not yet based on any comprehensive science. Reams of research link long-term small exposures of the contaminant to cancer risk. Few studies explore the potentials of short, intense household exposures.
'Right now, there's no chemical modeling, mathematical modeling or any exposure assessments that have been conducted to determine the answers to [these] questions,' said Andrew Whelton, a professor of civil environmental engineering at Purdue University and a leading researcher in the field of postfire water safety.
Read more: Scientists urge caution after a carcinogen is detected in water in fire-stricken areas
In California, while the maximum allowed level of benzene in drinking water is 1 part per billion, the Office of Environmental Health Hazard Assessment says the concentration needs to be as low as 0.15 ppb to confidently say there will be no long-term chronic health effects. For the short-term, the Environmental Protection Agency deems exposure to over 200 ppb for longer than one day dangerous.
In the aftermath of the recent fires, utilities in L.A. County have found levels as high as 190 ppb in Altadena and 71.3 ppb in the Palisades. However, after the Tubbs fire, Santa Rosa found levels as high as 40,000 ppb.
After Santa Rosa Water first tested its customer's kitchen faucet, the utility, along with the Division of Drinking Water and the EPA, launched a full investigation into the contamination of the drinking water of the affected area, and the results were unlike anything that had been seen before.
'We did a lot of research in the start to see if any other agency had experienced this,' said Jennifer Burke, director of Santa Rosa Water. 'We did not find anything anywhere.'
What Santa Rosa Water found — not in the literature, but in its own backyard — was that a whole range of potentially dangerous chemicals lurked in the water. The discovery has helped guide post-wildfire recovery since.
Santa Rosa Water first tried to figure out how a contaminant like benzene could've entered the water. The utility looked into whether nearby underground gasoline storage facilities could've been compromised, or if benzene was present in the soil, but found no compelling evidence. Then, a hypothesis emerged that would later be borne out in the lab and testing data from water systems postfire across the West.
Parts of Santa Rosa's water system had lost pressure during the blaze as firefighters tapped into hydrants, residents ran hoses to protect their properties and damaged connections spewed water into the street. As the water level dropped, leaving higher elevations dry, it created a void in the system. To fill the pressure void, experts theorized, the open connections began to suck toxic ash, soot and smoke into the pipes.
It meant the contamination had the potential to quickly spread far beyond one home. And wildfire smoke carries much more than just benzene. In it is every household toxic chemical that could've burned. It's a reality that poses a daunting task for scientists and utilities.
'We're chasing after a growing and an increasingly complex reality of living in the modern world, where we're creating all of these new chemicals all the time,' de Guzman said.
Among the complex sea of chemicals scattered through postfire burn areas, water safety experts have settled on a few groups of the most concerning contaminants based on their risks to humans and their presence in the Tubbs and Camp fires in California, the Marshall fire in Colorado and the Maui fires in Hawaii.
During previous fires, some experts argued testing for benzene alone is sufficient, saying the chemical, which time and time again has exceeded safe levels most often in postfire systems, acts as a good 'indicator' for whether other chemicals may be present.
However, with mounting evidence of other contaminants lurking in water systems postfire, even without benzene present, it's an increasingly rare position.
Most now argue that utilities ought to test not only for benzene, but at least the rest of its immediate family, called volatile organic compounds, or VOCs. Others say they should also test for VOCs' less-aggressive cousins, semi-volatile organic compounds, or SVOCs.
With higher boiling points than VOCs, SVOCs are less likely to evaporate, but still pose an inhalation and ingestion risk. SVOCs are not necessarily less toxic to humans.
Some VOCs and SVOCs — like the chemical responsible for the smell of pine in trees and car fresheners — are essentially harmless. Others, like benzene, are toxic to humans.
'I don't think [benzene] should be viewed as a perfect, comprehensive indicator, but it's very much a good start,' said Chad Seidel, an environmental engineering research affiliate at the University of Colorado, Boulder, and president of Corona Environmental Consulting, which assisted in the Marshall fire recovery. 'I will say this: It is dramatically better than what the responses have been, say, not that long ago — maybe more than five years ago, where nobody was doing any of this.'
In practice, many postfire water safety experts argue that to confidently say the water is safe for customers, utilities cannot rely on benzene alone.
'There is no evidence that benzene is an indicator of contamination. … It simply isn't,' Whelton said. 'Unfortunately, that misinformation has traveled and continues to travel into decision-makers' opinions.'
In 2023, the California state Legislature codified postfire testing for benzene into law. While only benzene testing is required, the state's Division of Drinking Water recommends that utilities test for the full range of VOCs — and the state, at times, has called benzene an 'indicator' for other contaminants.
For the Paradise Irrigation District, although testing for the full suite of VOCs can take slightly longer and cost a fair bit more, it was a pretty obvious choice (even amid pushback from the Division of Drinking Water and the EPA, at the time).
'We decided to go above and beyond,' said Kevin Phillips, district manager with the Paradise Irrigation District, 'because we wanted to give … our customers the utmost confidence that there were no other VOCs present in there.'
Yet, many customers, living with cold showers and bottled water for months on end, remain frustrated with the lengthy process and uncertain if their water is safe. It's why many water safety experts and utilities that have experienced postfire recovery have urged the L.A. utilities to remain as transparent as possible.
'The last thing any water system wants is … to create some urban myth that the water in this certain water system is not safe,' said Kurt Kowar, director of public works for Louisville, Colo., which was devastated by the Marshall fire. 'That can always stick with you, and if you can't be transparent and generate trust through recovery, I think that would be a disservice to the community — if they don't trust their water provided for the rest of their life.'
The Paradise Irrigation District created an interactive online map of its entire system and the location of every test taken. And the Los Angeles Department of Water & Power created an online dashboard a month and a half after the fires listing the number of VOC detections in each of its zones in the Palisades fire burn area and the levels detected.
Meanwhile, the smaller Altadena utilities, with limited personnel and resources, have been regularly posting joint updates to their websites outlining their recent testing, affected streets and the highest benzene levels found.
But none of the L.A. utilities have posted the full testing data with exact locations. Part of the communication problem is a lack of guidance and assistance from the state, said Gregory Pierce, director of the UCLA Water Resources Group.
That said, thanks to their much better understanding of the water contamination problem than in previous fires, the L.A. utilities have been optimistic about returning service far faster than they would have been a decade ago.
Once Santa Rosa Water understood the problem it had on its hands, it started by aggressively flushing its system — opening up hydrants and valves to purge water through the entire network of pipes, hoping the released water would take the contaminants with it. While it worked for many areas within the burn area, the hardest-hit region proved difficult. By the time the city had gotten to flushing, benzene had bound itself to the pipes.
Santa Rosa was forced to replace not only service lines to individual homes, but some of the main lines along the street as well.
The L.A. utilities have been betting on flushing alone. It's a strategy that seems to have worked — in part because they knew what steps to take earlier than utility companies in previous wildfires.
In the Palisades, full service has already been restored. The Altadena utilities have made significant progress and remain hopeful they'll be able to restore safe water much faster than the year it took Santa Rosa and the eight months it took Paradise.
On the one-month anniversary of the fires, LADWP hesitantly and optimistically said it hoped to restore safe drinking water to the Palisades by the end of February. It succeeded in doing so on the two-month anniversary — only one week later than the estimate.
'How you can get your customers back to their homes with the utilities they need? It is a heroic effort to pull those things off,' Seidel said. 'I applaud those people that are willing to step up and pull off what it takes to do those things. It's not easy.'
This story originally appeared in Los Angeles Times.