Two months after wildfire burned through Paradise, California in 2018, Kevin Phillips, then manager of the city's irrigation district, walked from one ruined home to another.
Burned-out cars, the occasional chimney, and the melted skeletons of washers and dryers were the only recognizable shapes.
"You actually started to be shocked when you saw a standing structure," he said.
Mr. Phillips, now the Paradise City Administrator, followed the team, taking samples from intact water meters attached to houses that were now reduced to gray ash. He knew from the Tubbs Fire in 2017 that harmful toxins are likely in the water distribution system: rapid action would be needed to protect those returning to the community from the dangers of toxins like benzene, which can cause short-term nausea and vomiting, or even cancer in the Over time.
Forest fires, which this year colored the skies over cities from Seattle to Santa Cruz dark orange, are increasingly devouring people's homes and have raged on in California, Oregon, Washington and Colorado in recent weeks. But even if houses don't burn, other hazards arise as a result, and experts are more focused on what happens to municipal water systems after a fire, when released toxins get into plumbing systems and other damage can linger in the pipes for years.
After the Paradise Fire, for example, tests published in a new study showed benzene levels in drinking water of 2,217 parts per billion. The Tubbs fire resulted in values of up to 40,000 parts per billion. California health Authorities say 1 part per billion is dangerous in the long term, and 26 parts per billion is dangerous for short term exposure. And many other compounds that end up in the water after a fire can also pose health risks.
"It's hard enough having the pandemic restrictions," said Angela Aurelia, a Boulder Creek resident in Santa Cruz County, whose home was partially damaged in August. "And then you have wildfire and you lose access to your house and then we can't even go home because the water is probably not safe."
Mr Phillips and a few others who keep the water flowing into their homes safe say they are following guidelines not designed for this type of disaster.
After a fire, water in homes and the pipes below can be "contaminated with a variety of volatile organic compounds and low-volatile organic compounds," in amounts that exceed legal limits set by the state of California and the federal environmental protection agency said Amisha Shah, a water quality engineer at Purdue University. "It is very clear that it needs to be addressed."
Volatile organic compounds such as benzene, naphthalene and methylene chloride have a low boiling point and can easily be dispersed in the air. Semi-volatile substances, including chrysene and benzo (b) fluoranthene, have a higher boiling point, but can be dispersed, for example, during a warm shower. While not all of these compounds are harmful, some have been found to cause cancer over the long term.
Dr. Shah co-authored the study published in July by AWWA Water Science, which summarized the lessons learned over the past few years. When analyzing the sample data from the Tubbs fire as well as the campfire that destroyed paradise, the researchers found some of these harmful toxins caused by forest fires throughout the distribution system. Previous concerns had centered on ash running off into water sources such as reservoirs.
The researchers 'observations were consistent with Mr. Phillips' experience in Paradise two years ago.
"Over 50 percent of these utilities from burned structures had some contamination," he said.
But he noticed that there was some coincidence. The water in one house would be contaminated while the neighboring system would be clear.
State regulations seemed inadequate to deal with a post-wildfire scenario, and forced Mr. Phillips and his team to effectively improvise their own standards.
"We went beyond what the Water Board might have asked of us," he said.
If they hadn't, he said, it would have taken years, if not decades, to have clean drinking water in the city again.
How water moves through distribution systems, especially during wildfire, is complex and needs further study. Dr. However, Shah and the other authors of the study say that a pressure drop that occurs when fires damage the pipes turns the plumbing into a vacuum that sucks smoke and other toxins from burning houses. These toxins are then circulated throughout a community's water distribution system. For example, things can get worse if firefighters use a nearby fire hydrant, a necessary step that is effective in promoting blood circulation.
In addition to the toxins that continue to spread through these charred buildings, plastic pipes, common in mountainous California areas, release toxins when heated, melted, or burned. The study authors said that such pipelines, even if not damaged, could absorb toxins that would end up in the water over a long period of time.
For example, in the San Lorenzo Valley, 12 km of high density polyethylene pipes burned and were burned and destroyed on August 21. The above-ground pipes that meandered through a steep, wooded mountain in Santa Cruz County supplied water to more than 21,000 residents.
During the chaotic aftermath of wildfire destruction, water district members can feel overwhelmed and confused about how to safely reuse a system. While many local water districts and other water utilities check for volatiles, most do not check for semi-volatiles.
In the case of the pipes from the San Lorenzo Valley, for example, regulators were ordered to only look at the 80 or so compounds in the E.P.A. Although it has been proven that burning plastic pipes also releases some semi-volatile substances.
The advice given to residents was also inconsistent. While the state recommends using "no use" when there is "an unknown pollutant", most utilities are advised to issue "no drink, no cook" to prevent ingestion. However, scientists fear that even showering or washing may not be safe if the water is high in compounds. Some toxins can be inhaled when the water is aerosolized.
Rick Rogers, the district chief of the San Lorenzo Valley Water District, said it was "following state regulation on the letter." They gave orders, "Do not drink, do not cook," but were not instructed to give "Do not use" orders.
The district's notice issued on Aug. 29 told residents that they could shower but "limit showering time" and "ventilate the area well." It was also recommended that "the safest option is to use alternative water for showering". At public gatherings, residents expressed confusion about the arrangements. Subsequent tests found benzene in the valley's water supply.
Since 2014, the State of California has placed responsibility for water safety in the hands of the State Water Resources Control Board.
The applicable regulations for local water suppliers are designed for normal everyday life. The tests recommended by the Board are aimed at finding routine contaminants. Since there is no set of rules for a forest fire disaster, the rules do not take into account all of the toxins that scientists now recognize as forest fire failure.
In some cases, the State Board has recommended tests that only look for benzene, which they believe is an important flag for other contaminants.
"Benzene has been the leading indicator of contamination in all cases where combustion products have entered the water system," said Stefan Cajina of the Board's Drinking Water Department.
He added that tests for semi-volatile impurities might be useful, "but in our experience they probably won't be there unless benzene is also present."
Many scientists disagree with this assumption, and the data Dr. Shah and her colleagues examined showed carcinogenic semi-volatiles when benzene was not present.
"There's enough information to be careful," said Fernando Rosario-Ortiz, director of environmental engineering at the University of Colorado, Boulder, who was not involved in the study. "It definitely teaches the water utilities that if you go through a case like Santa Rosa and the Paradise Fire, you should definitely do additional testing under those criteria."
The state values time and efficiency in an emergency and advises water utilities to test the toxins that are most likely to be found. Mr Cajina said testing for other toxins, like the semi-volatiles, might take more time and cost more.
"These types of tests may be better suited for long-term studies than an immediate active fire response," he said.
But like Dr. Shah and colleagues in their study report that other potentially harmful toxins were later found when fires burn houses and pipes. If there is no contamination, it can quickly spread throughout the system.
"Time is of the essence when residential units or places they want to use water do not allow them to open the tap and then expose themselves," she said.
Part of the problem is the lack of clear authority during the state of emergency, with authority over water remaining divided among various federal and state agencies.
"There is no water-specific mission in the national response framework," said Kevin Morley, federal relations manager for the American Water Works Association. With so many departments monitoring the water in an emergency, it becomes difficult to establish clear authority, direction, and support.
Other states are now turning to California guidelines and regulations to learn how to handle forest fire safety. An Oregon agency last month released a guide to testing for volatile organic compounds that appears to echo California's recommendations and copy some of the issues scientists have warned about.
As forest fires worsen and become more common, experts like Dr. Shah has clear federal or state guidelines that local water companies can follow.
They recommend testing for a variety of connections in all water systems and ordering that residential water be used only when results are available. Preventive measures like installing one-way valves on home water meters and shutting down water systems before there is a risk of fire could isolate the contamination. The San Lorenzo Valley Water District, for example, has shut down part of its system, which may have helped prevent it from spreading.
Mr Phillips said states and cities need to be better prepared for the unknown given the ongoing threat of forest fires.
"You have to stress test the worst-case scenario and then come up with an answer."