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 last year fires scorched the United States, and 2021 is on track to level out Dryer. What many people don’t realize is that these wildfires can do lasting damage away from the flames – they can contaminate entire drinking water systems with carcinogens that persist for months after the fire. That water flows into houses and also pollutes the sanitary facilities.

Over the past four years, wildfires have contaminated drinking water distribution networks and pipeline construction for more than 240,000 people.

Small water systems for housing projects, mobile home parks, businesses and small towns have been particularly hard hit. Most didn’t realize their water was unsafe until weeks to months after the fire.

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

Like a environmental engineer, I and my colleagues work with communities recovering from forest fires and other natural disasters. Last year, at least seven water systems were found to be contaminated, suggesting that drinking water pollution may be a more widespread problem than people realize.

Our new study identifies critical issues that households and businesses must be aware of after a wildfire. If you don’t address them, it can harm people’s health – mentally, physically, and financially.

Forest fires make drinking water unsafe

In forest fires damage water distribution pipes, wells and plumbing in homes and other buildings, they can pose immediate health risks. A building’s plumbing can become contaminated by smoke drawn into water systems, due to heat damage plastic pipes – or contamination that enters the plumbing and leaches out slowly over time.

Since 2017, multiple fires have made drinking water systems unsafe, including the Echo Mountain, Lionshead and Almeda fires in Oregon, and the SENSE 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 cause a decrease in the number of white blood cells that protect the body against infectious diseases. Multiple fires have caused drinking water to exceed this level. A variety of other chemicals may also exceed exposure limits for safe drinking water in the absence of benzene.


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

Households are not sufficiently warned

In a survey of 233 households affected by water pollution, we found that people reported high levels of anxiety and stress associated with the water problems. Almost half had installed water treatment in their homes due to uncertainty about the water. Eighty-five percent had looked for other water sources, such as bottled water.

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

After the 2020 CZU Lightning Complex Fire near Santa Cruz, California, a local health department correct well warned owners did not use and test their water, but a nearby damaged water system and the state did not warn 17,000 people about it to bathe in the polluted water. Only after the test results showed that the water had been unsafe all this time was it not recommended by the system owner and the state to bathe in the.

In Oregon, some damaged systems were encouraging people B ‘oil their drinking water, and later discovered that the water contained benzene.

After the 2018 campfire that devastated Paradise, California, the local health department rightly warned the entire county not to use or attempt treat the drinking water, which had a contamination level higher than the EPA hazardous waste limit. But one water system and the state encouraged 13,000 people to try that treat it yourself.


Pipes, water meters and meter covers after they were destroyed by wildfires.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 has chosen not to explicitly coerce water companies notify customers about the water pollution and the risk thereof.

Communities have received other bad information:

  • Advertisement labs and government officials recommended flushing faucets for 5 to 15 minutes before collecting a water sample, discarding contaminated sanitary water intended for testing.
  • Home owners were LED to believe that a single sample of cold water at the sink would determine if the property’s hot water system and service line were contaminated. It’s not possible.
  • People were LED to believe that testing with benzene water would determine if other chemicals were present above safe limits. This is not possible.

What to look for after a fire in the area

Signs of possible contamination after a nearby wildfire 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, cleaning it up can take months. The water system will have to be flushed and tested regularly to detect this contamination. Health departments should also provide guidelines on testing private wells and plumbing.

When testing plumbing, include the property service line as well as the hot and cold water lines. Before collecting a water sample, the water must sit in the pipes long enough for contamination to be found – 72 hours was the Tubbs Fire and Camp Fire standard. Tests should look for more than just benzene.


Construction water systems can receive polluted drinking water from public water systems and private sources. Andrew Whelton / Purdue University, CC BY-ND

Who can help?

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

Public health departments are often experienced in addressing water issues, such as Legionella outbreaks, and can provide technical advice on both chemical exposure, building sanitation and private drinking water wells.

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