Bushfires pose serious short- and long-term impacts to public drinking water quality and the consequences could last for decades, say experts.
“(Bushfires) can damage water supply infrastructure and water catchments, impeding the treatment processes that normally make our water safe to drink,” Stuart Khan, Professor of Civil and Environmental Engineering, UNSW wrote in the online journal The Conversation.
Several areas in New South Wales and Victoria were issued with warnings about the quality of their drinking water during January.
In the short-term, bushfires can damage or disrupt water supply infra-structure as they burn. And the risks can persist after the fires are out, says Prof Khan.
“A loss of power, for example, disables important water treatment processes such as chlorine disinfection, needed to kill microorganisms and make our water safe to drink.”
Drinking water for the towns of Eden and on the NSW south coast was affected in this way. Residents were advised to boil their water before drinking it and using it for cooking and brushing their teeth.
Other towns, including Cobargo, received similar warnings on New Year’s Eve.
In the long-term bushfires can damage drinking water catchments, which can lead to longer lasting threats to drinking water. Drinking water catchments are typically forested areas, and so are vulnerable to bushfire damage.
“Severe impacts to waterways may not occur until after intense rainfall. Heavy rain can wash ash and eroded soil from the fires into waterways, affecting drinking water supplies downstream,” says Khan.
“Impacts to catchments from bushfires and subsequent erosion can have long-lasting effects, potentially worsening untreated drinking water quality for many years, even decades.”