Wildfires Threaten City Water Supplies: The Rising Danger of Contaminated Drinking Water

Wildfires in Los Angeles have led to dangerous levels of contamination in drinking water supplies. While the flames rage, some utilities have warned residents that their tap water may not be safe to drink until further tests are conducted.

As our climate warms and becomes drier, the risk of wildfires increases. These fires can severely damage water systems in urban areas. According to experts, harmful chemicals released from burning buildings can seep into these systems. Traditional methods like boiling or filtering may not remove these toxins.

Recently, Pasadena Water and Power issued a rare “Do Not Drink” alert to about one-third of its customers. This decision came after significant damage was done to some water infrastructure, including burned pumps and storage tanks. Safety first: “You kind of have to assume the worst,” said Stacie Takeguchi, the utility’s chief assistant general manager.

Fortunately, after testing, they lifted the warning for most areas. But why do urban fires pose such a threat to drinking water?

When fires break out in cities, they can wreak havoc on essential infrastructure. The intense heat can cause ash, soot, and smoke to enter water pipes, creating contamination. Andrew Whelton, an engineering professor at Purdue University, highlights that materials used in buildings release toxic particles during a fire, which can penetrate the water supply.

Normally, water systems maintain pressure to keep contaminants out. However, fires can disrupt that pressure for many reasons. While some residents stay put and continue using water, firefighters also use massive amounts. Furthermore, if power goes out, pumps may fail, causing more pressure loss. This scenario played out during the recent fires in Maui.

In addition to safety concerns, this loss of water pressure makes it harder to fight fires. For example, during a recent wildfire in the Pacific Palisades, hydrants ran dry, which shocked both firefighters and local residents. Investigations into the cause are ongoing.

The health risks from toxic chemicals in drinking water are serious. They range from mild symptoms like nausea to severe conditions, including cancer. With past fires, such as the 2018 Camp Fire in Paradise, California, dangerous chemical levels were reported, especially benzene, which is known to cause blood disorders in children.

Even very low levels of benzene are concerning. California regulators define a safe level as just one part per billion, based on long-term exposure. Cumulative exposure is what matters, and a short-term spike during a fire can increase long-term risks significantly.

In Louisville, Colorado, after the 2021 Marshall Fire, contamination from semi-volatile organic compounds was found in water pipes, even when more well-known toxins like benzene were absent. Testing for all potential contaminants is essential.

As fires continue to threaten urban areas, Los Angeles County has over 200 water service providers, but only a few have issued “Do Not Drink” warnings so far. Utilities are primarily focused on ensuring water for firefighting, while testing for contaminants is just beginning. It can take weeks or even months to declare water safe again.

The aftermath of the Paradise fire exemplifies the challenges faced. Most buildings were lost, leaving the city to spend years and millions of dollars replacing contaminated infrastructure.

Experts advise against private water testing until public systems are confirmed safe. Most home testing kits are not designed to detect fire-related contaminants. Once utilities give the green light, professional testing is recommended to check for any lingering issues.

It’s crucial for residents to follow guidance from utilities and local health departments during these uncertain times. Stay informed, stay cautious, and prioritize safety until water systems are declared safe.

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