Wildfires and Water Quality: VOC Contamination

Concentrations of benzene—a known carcinogen—were found at 40,000 parts per billion (PPB) after the Tubbs Fire and more than 2,217 PPB after the Camp Fire. 

California health agencies have stated that children exposed to benzene levels as low as 26 PPB can experience short term health effects. Because cancer is long-term risks of benzene exposure, California’s Public Health Goal for benzene in drinking water is 0.15 PPB (which is about the equivalent of less than 1 drop of water in an Olympic-sized swimming pool). 

How Do Wildfires Spread VOCs to Drinking Water?

The Tubbs and Camp Fire in California are the first studied cases showing widespread chemical contamination in the water distribution network itself and not in the source water. Pipes inside buildings and buried underground were heavily contaminated.

More research is needed, but evidence currently suggests that this contamination came from a mix of burning vegetation, structures, and plastic materials. 

Wildfires like these are so hazardous and destructive because they happen in areas where human development meets wildlife. These events fall into a category of hazards called “Natech,” or natural disasters that lead to technological disasters, like the release of toxic chemicals.

How Can You Tell If Your Water Is Contaminated After a Wildfire?

Health officials are still putting together policies for keeping residents safe after major wildfires.

However, agencies have struggled to perform sufficient water testing following these disasters. 

After the Camp Fire, California officials told residents to check for odors to indicate whether there were harmful chemicals in the water—even though VOCs like benzene can create health risks at lower concentrations than what’s detectable by smell.

Water quality experts have stated that only testing can determine safety, and that all buildings should be tested after a wildfire. Reliable testing also needs to include samples of both hot and cold water from many taps in a building because water quality can vary greatly between rooms.

It’s also important to note that most utilities are responsible only for testing the service lines up to the customer’s connection (typically at the curb box/water meter). Customers are responsible for testing the water quality in their homes after that connection point.

How To Protect Drinking Water After a Wildfire

After the Camp Fire, researchers estimated that some plastic pipes needed more than 280 days of flushing before they were safe to use again. As of March 2020, 8.5% of water tests still detected benzene and/or other VOCs.

For areas that have gone through a major wildfire, “do not use” orders can keep people safe until local health agencies can test the water.

Boiling advisories and household water filters are not enough to protect residents from highly contaminated water.

Does Boiling Water Remove VOCs?

Boiling tap water is only effective for certain VOCs, and should not be relied on as a treatment option.

Because VOCs easily evaporate, these chemicals aren’t only a health risk for drinking—boiling water (and even hot showers) can vaporize VOCs and create air quality hazards. 

Can Water Filters Remove VOCs?

Activated carbon filters can remove many VOCs, but these filters may not be suitable for the high levels of chemical contamination after a wildfire. 

Carbon filters need to be monitored and replaced more frequently when they are treating high or repeated doses of contamination. Point-of-use (POU) carbon filters—like those used in refrigerators and on faucets—have an even shorter life span than whole house filters. 

All filters should go through frequent testing while local drinking water is contaminated. The EPA’s guidance for Point-of-Use or Point-of-Entry Treatment Options suggests monitoring filters monthly.

It’s also important to note that POU devices only protect the taps they are filtering. In addition to posing an air quality hazard, some VOCs can also be absorbed through the skin. This leaves water coming from shower heads and other untreated household faucets a potential hazard.

Can Wildfires Contaminate Private Wells?

Private wells are also at risk of damage and contamination from wildfires. You should always test your well water after any changes in water appearance, clarity, color, smell and/or taste.

Contact a licensed well contractor if you see any of damage to: