When a wildfire leveled a whole neighborhood in Santa Rosa, California, in October, it was just the first disaster for this Wine Country city. A second disaster is now unfolding after chemical contamination was detected in the city’s drinking water following the fire.
The Tubbs Fire, part of a trio of fires known as the Central LNU Complex, destroyed more than 5,600 structures and killed 23 people. The first neighborhood it hit was Fountaingrove, an enclave of expensive homes strung along scenic ridgetops. More than 300 homes in the neighborhood burned to the ground.
Soon afterward, some Santa Rosa residents began to smell chemicals in their drinking water.
City officials tested some 2,000 water samples after the fire, and have now concluded the contamination came from plastic water supply pipes that melted in the fire. The primary contaminant is benzene, a petrochemical found in some plastic pipes, particularly those made of HDPE plastic.
Plastic water pipes have come under scrutiny in recent decades amid concerns that harmful chemicals may leach from some kinds of pipe. Santa Rosa’s problem, however, is the first known case of plastic pipes causing widespread water contamination after a fire.
“We now know that the combustion, the burning, the melting of various plastic components in our distribution system gave off constituents that got into the water system,” said Bennett Horenstein, Santa Rosa’s director of water. “We’re finding a very broad spectrum of chemicals that were released as the plastic burned, with benzene being the leading contaminant and the leading issue in terms of public health exposure.”
The city quickly identified the burned Fountaingrove neighborhood as the source of the contamination, and sealed off that part of the water system to prevent contamination from reaching the rest of the city.
Thirteen Fountaingrove homes survived the fire and remain exposed to the contamination. The city has warned those residents not to consume the water, and is providing them bottled water on a temporary basis.
The long-term solution, said Horenstein, involves replacing the entire water supply system in the affected Fountaingrove neighborhood, including underground water mains that did not melt. That could cost $40 million, he said, and take two years to complete under a best-case scenario.
Because the fire led to a federal disaster declaration, Horenstein hopes the Federal Emergency Management Agency will help cover the cost of water system replacement. But that remains uncertain at this point.
Benzene is a toxic petroleum constituent known to cause cancer and neurological problems. It is also found in tobacco smoke. The state of California’s health standard for benzene in water is 1 part per billion. Some samples taken from the Fountaingrove neighborhood after the Tubbs Fire detected benzene at 80 times that limit.
Horenstein said there’s nothing unique about Santa Rosa’s water system or the materials used in its plumbing. Thus, it offers a cautionary tale for other communities.
“When you have an event like this, you should really immediately sample your water system for potential hydrocarbon contamination,” he said.
Plastics have become ubiquitous in water systems. Virtually every component of a water distribution system includes some plastics, from the water meter at every home’s curb to valves in kitchen and bathroom faucets. Even fire hydrants contain some plastic components, Horenstein said.
Modern water mains in the street are often plastic as well, replacing concrete or steel mains common a century ago.
It appears Santa Rosa’s contamination occurred in a two-part process, Horenstein said.
First, plastic water system components in homes – faucets, water lines in walls and crawl spaces – burned and melted in the fire. In some cases, water meters and supply lines between the curb and the house – generally installed at shallow depth – also melted.
Second, the enormous water demand created in battling the fire led to negative pressure in some parts of the water system. This allowed chemicals from the melted plastics to be drawn into the water system and spread.
A third factor, Horenstein said, is that even though plastic water mains were not directly damaged by the fire, the chemicals drawn into the system may have attached themselves to the walls of these larger pipes.
This created a lasting contamination problem that continues today and is the main reason the city must consider total replacement of the water system in this area. Flushing or scrubbing the mains doesn’t eliminate the pollution, because it becomes embedded in the pipe.
“Those benzene, toluene, xylene molecules do not penetrate copper,” said Andrew Whelton, an assistant professor of engineering at Purdue University who studies plastic pipes. “Plastic is more like a sponge. It has pore spaces, the atoms are not as densely compacted. The chemicals generally like to be in the plastic and not so much in the water.”
Plastic pipes, in other words, are permeable.
Plastic water pipes have become so popular because they are generally much easier and cheaper to install. For instance, PEX pipe, one of the newest plastics in residential plumbing, is very flexible. Rather than opening a wall to install rigid copper pipes – which use soldered joints – PEX can be snaked through walls using small openings. It also uses joints and fittings that can be installed by most any do-it-yourselfer.
The industry conducts its own product testing using a nonprofit called NSF International (formerly known as the National Sanitation Foundation). Whelton, a principal investigator at Purdue’s Center for Plumbing Safety, said the testing protocol doesn’t necessarily reflect real-world conditions.
For example, the protocol repeatedly flushes water through a pipe over a period of 17 days, then only tests the water for contaminants at the end of that period. As a result, Whelton argues, the tested pipe is first cleansed of chemicals that might initially leach from the plastic before being tested. This does not reflect real-world conditions, he said: Most homeowners can’t wait 17 days to start using their tap water after having new pipes installed.
The foundation also does no testing to simulate disaster situations, like fires, or to measure permeability after plastic pipes are exposed to chemicals. And it does not make any of its test results available to the public.
Dave Purkiss, vice president of global water systems at NSF International, said its test results are not made public to protect the trade secrets of the companies that submit materials for testing. He defended the organization’s testing protocol, and said it is willing to consider new testing methods.
“Anybody from the public can suggest a change,” said Purkiss. “It is a dynamic standard. Based on this issue, you could propose a change in the standard to measure external heat or permeability. But today, it’s really just focused on ensuring the new product being installed by plumbers or water utilities would not be adding contamination to water.”
As a result of NSF’s privacy policies, there is no resource Santa Rosa could consult to find out what chemicals might be leaching from residential pipes, what kinds of pipes might be responsible for those chemicals, or even to study prior cases of chemical leaching from plastic pipes.
“One of the issues is that there’s really no independent organization that’s tracking these types of incidents,” Whelton said. “For example, the U.S. EPA does not regulate or oversee plumbing material performance. There is really a deficient amount of data out there about what types of chemicals can be released from plastic pipes.”