As California battles wildfires that seem fiercer, larger, and longer each year, cities around the state are tackling fire prevention and recovery. The main injuries from fires are obvious: loss of life and property, poor air quality, and damaged environments. Yet there are less obvious, more insidious consequences of wildfires that can be just as serious. One such example is water contamination from man-made sources, not just ash pollution, char, and sediment.

As a wildfire moves through a community, it can rupture fire hydrants, burn meter boxes, and melt pipes. Pollutants from burning vegetation and buildings, as well as melted plastic, burnt building materials, and fire-fighting chemicals leach into the water supply. That water may be used for firefighting, spreading the contaminated water to new places, or for drinking, causing discomfort, severe illness, or death.

The risk of water toxicity does not diminish when the fire is gone. Pollutants linger once the flames have been put out, collecting in surface water, or leaching into groundwater. Pipes made of plastic and other materials may absorb chemicals from the first burst of contaminated water that flows through the pipes, then slowly leach the absorbed chemicals back into clean water that moves through the pipe. Depending on the material, plastic pipes or plastic components of water systems can melt or decompose, sending chemicals into the water. Airborne toxic chemicals may be sucked into water systems during periods of low pressure, then vaporized in hot water, making hot showers or boiling water on the stove riskier than usual.

So how can cities combat these dangers? First, building codes can be utilized to improve wildfire safety in buildings. Tools such as backflow prevention devices or fire-resistant meter boxes can decrease chemical leaching and melting plastic. Local building codes can be updated to incorporate fire-safe building materials or water systems less likely to absorb toxic chemicals. Second, spreading information and combating misinformation about the dangers of post-wildfire recovery is critical when preventing illness or death due to toxic water. Cities can boost information about water safety in the period during and after a fire on social media, informing their population on minimizing exposure to pollutants, thereby saving lives. Finally, coordinating with water regulators and agencies to test, retest, and test again before allowing citizens to resume use of water. Examining the local water supply post-wildfire can ensure that cities understand the state of their water supply and provide accurate information about toxicity levels to their citizens.

When it comes to preparing for fire season, a comprehensive approach is needed. Even though water toxicity is less immediate than fire safety, it can be a crucial piece of the fire recovery puzzle. Every bit a city does to prepare may save a life.

For the water toxicity study, please visit https://awwa.onlinelibrary.wiley.com/doi/full/10.1002/aws2.1183