Wildfires are contaminating drinking water systems, and it’s more widespread than people realize

Source: Santi Rodriguez / shutterstock

By Andrew J. Whelton

More than 58,000 fires scorched the United States in the past year, and 2021 is well on the way to getting even drier. What many people fail to realize is that these forest fires can cause permanent damage beyond the reach of the flames – they can contaminate entire drinking water systems with carcinogens that last for months after the fire. The water flows to the houses and also pollutes the plumbing.

In the past four years, forest fires have contaminated drinking water distribution networks and sanitation for more than 240,000 people.

Small water systems for housing estates, mobile home parks, businesses and small towns are particularly affected. Most of them didn’t realize until weeks to months after the fire that their water was unsafe.

The problem starts when devastating smoke enters the system or plastic heats up in water systems. When heated, plastics can release harmful chemicals such as benzene, which can contaminate drinking water and permeate the system.

As an environmental engineer, I and my colleagues work with communities that are recovering from forest fires and other natural disasters. Last year, at least seven water systems were found to be contaminated, suggesting that drinking water contamination is a more widespread problem than people believe.

Our new study identifies critical issues that households and businesses should consider after wildfire. If not addressed, it can affect people’s health – mentally, physically, and financially.

Forest fires make drinking water unsafe

When forest fires damage water distribution pipes, wells, and plumbing in homes and other buildings, they can create immediate health risks. A building’s plumbing can be contaminated by smoke drawn into water systems, heat-damaging plastic pipes, or contaminants entering the plumbing and slowly leaching out over time.

Since 2017, several fires have ravaged drinking water systems, including the Echo Mountain, Lionshead, and Almeda fires in Oregon and the CZU Lightning Complex, Camp, and Tubbs fires in California. Thousands of private wells are also affected.

Exposure to contaminated water can cause immediate damage such as headache, nausea, dizziness, and vomiting. Short-term exposure to 26 parts per billion or more of benzene, a carcinogen, can lead to a decrease in white blood cells, which protect the body from infectious diseases. Several fires have caused the drinking water to exceed this level. A variety of other chemicals can exceed exposure limits for safe drinking water even in the absence of benzene.

Maximum benzene content in parts per billion
Table: The Conversation / CC-BY-ND Source: Andrew WheltonRetrieve the data

Households are not given sufficient warning

In a survey of 233 households affected by water pollution, we found that people reported high levels of anxiety and stress related to the water problems. Almost half had installed a domestic water treatment system because of the uncertainty about the water. 85 percent had looked for other sources of water, such as bottled water.

In some cases, we found that advice from government agencies put households at greater risk of harm. It has exposed people to chemicals at times, causing them to spend money unnecessarily and making them feel false. For example, certified household water treatment devices are only tested to reduce 15 parts per billion benzene to less than 5 parts per billion, the federal standard. These devices have not been tested for treatment of hazardous waste contaminated water found after forest fires.

After the 2020 CZU Lightning Complex fire near Santa Cruz, California, a local health department correctly warned private well owners not to use and test their water, but a nearby damaged water system and the state did not warn 17,000 people about that Bathing in the contaminated water. It was only after the test results showed that the water was unsafe all along that the system owner and the state advised against bathing in it.

In Oregon, some damaged systems encouraged people to boil their drinking water and later found the water contained benzene.

In the aftermath of the 2018 camp fire that devastated Paradise, California, the local health department rightly warned the entire county not to use or treat the drinking water that was contaminated above the EPA hazardous waste limit. But a water system and the state encouraged 13,000 people to try to treat it themselves.

Pipes, water meters and meter covers after forest fires destroyed them. Caitlin Proctor, Amisha Shah, David Yu and Andrew Whelton / Purdue University, CC BY-ND

In all of these cases, the U.S. Environmental Protection Agency decided not to force water utilities to explicitly notify customers of the water pollution and its risk.

Communities received other bad information:

• Commercial laboratories and government officials recommended flushing the faucets for 5 to 15 minutes before taking a water sample in order to drain the contaminated sanitary water earmarked for testing.
• Homeowners were led to believe that a single cold water sample at the sink would determine if the hot water system and property utility line were contaminated. It can’t.
• People were led to believe that benzene water tests would determine if other chemicals were present above safe limits. This is not possible.

What to look out for after a nearby fire

Signs of possible contamination after a nearby forest fire can include loss of water pressure, discolored water, heat damage to water systems inside and outside buildings, and broken and leaking pipes, valves and hydrants.

Drinking water should be considered chemically unsafe until proven otherwise.

Once a system is contaminated, it can take months to clean up. The water system must be flushed and tested regularly to detect any contamination. Health departments should also provide guidance on testing private wells and pipelines.

When testing plumbing, consider property plumbing and hot and cold water pipes. Before collecting a water sample, the water must sit in the pipeline long enough for contamination to be detected – 72 hours was the standard for Tubbs Fire and Camp Fire. Tests should look for more than benzene.

Building water systems can receive contaminated drinking water from public water systems and private wells. Andrew Whelton / Purdue University, CC BY-ND

Who can help?

Many of the critical public health risks identified in our new study can be addressed by health departments with funding from state and local authorities.

Public health authorities are often experienced in responding to water problems such as Legionella outbreaks and can provide technical advice on chemical exposures as well as building plumbing and private drinking water wells.

CC BY-ND 4.0