Experts are looking into water quality in municipal water systems after a wildfire, when toxic chemicals are released and contaminate the water supply, warning that existing regulations are not suitable to address emergency situations such as the aftermath of wildfires, reports the New York Times.
Residents whose houses have been damaged by a wildfire have another hurdle when trying to get back home: water may not be safe to use. Benzene, for example, was found at dangerously high levels in the drinking water of the town of Paradise (California) after a wildfire destroyed it in 2018, reaching 2,217 parts per billion (PPB), or as high as 40,000 ppb after the fire in Tubbs, also in California. Just 1 ppb is dangerous in the long-term, according to Californian authorities, and 26 ppb could be dangerous in the short term. And there are also other compounds of concern which could end up in the water.
A common concern for the water supply after a wildfire is the possibility of ash runoff ending up in reservoirs used as a source of water. But researchers have also found harmful chemicals, like some VOCs and semi-VOCs, in the water distribution network. A study published in AWWA Water Science concluded that as wildfires at the wildland–urban interface are likely to occur more frequently, greater scientific evidence is needed to guide responses that will better protect public health. Study co-author Dr Shah and her colleagues believe the loss in pressure that occurs when fires damage pipes turns the plumbing into a vacuum, sucking in smoke and chemicals from burning homes, which afterwards are circulated through the water system. In addition, plastic piping, used in some areas, can release chemicals when heated or burned.
In the aftermath of a wildfire, authorities may issue orders not to drink or boil water, but even taking a shower may not be safe. The regulations in place are designed for day-to-day activity, and do not take into account all the toxic substances that researchers are now finding as a result of a wildfire. Benzene has been used as an indicator of contamination where combustion products may have contaminated the water system, as part of the immediate response, according to Stefan Cajina of the California Water Resources Control Board. He said other type of testing might be more appropriate for long-term study. But Dr Shah and colleagues saw that other harmful chemicals, such as carcinogenic semi-VOCs, can also be found, even when no benzene was present; if not contained, contaminants can spread through the system.
Contributing to the problem is that, during an emergency, there is no clear authority overseeing water matters, with various departments involved instead. As the scale and intensity of wildfires across the western U.S. increases, linked to climate-related changes, experts like Dr Shah call for clear guidelines that local water utilities can follow to ensure the safety of the water supply.