What do bushfires mean for Australia’s water supply?

This bushfire season has seen extreme pressure on water sources already under stress from drought. Water contamination and shortage present serious risks to Australians’ long-term health, Aparna Lal writes.

The Australian bushfires are continuing to impact Australia’s environment and public health in a variety of ways, one of which, though less discussed, is water quality. The contamination of drinking water and the quantity of safe water available for households is presenting a serious risk to long-term public health.

This is not a totally new phenomenon – previous bushfire seasons have resulted in shorter term impacts for water security, especially when it comes to quantity of drinking water available. But long-term effects are not something the country has seen before, and it’s not certain how decreasing water quality and quantity will impact public health in the medium-to-long term.

There is some data though, and data on extreme events, water quality, and health outcomes can tell us much about the sorts of public health issues that Australia might be looking at into the future.

More on this: Live blog: Bushfire analysis and opinion

Research shows that extreme weather events can impact the quality of drinking water. This includes increased concentration of bacteria and other microbial contaminants, changes to turbidity, and changes to colour and smell.

In Australia, there have been strong examples of increased concentration of phosphorous and total nitrogen following bushfires compared to average pre-fire levels.

Additionally, for communities connected to town water supplies, the loss of power to stations can reduce water pressure in distribution systems, a known risk for the contamination of drinking water.

Such changes can result in increased public health risks that include outbreaks of gastroenteritis, eye and skin infections. In addition, when drinking water sources are used to fight bushfires, as we are seeing right now, the limited quantity of clean water to communities becomes problematic.

This means it’s especially important that affected communities are supported to protect themselves from unclean water following an extreme weather-related event.

In the short-term, drinking water issues can be mitigated, but the longer-term public health impacts of fires on drinking water are not as clear.

More on this: Declaring a water emergency

When considering the medium-to-long-term health implications of water quality and availability, the data is limited to developing nations, especially those in Africa and South-East Asia, where clean drinking water and sanitation are ongoing public health and developmental issues.

Unsurprisingly, long-term inadequate access to clean water has been shown in these places to negatively impact public health. Chemical contamination, with substances like nitrates and arsenic, of drinking water is associated with an increased risk of cancer, chronic kidney disease, and psychosocial stress. The World Health Organization estimates 829,000 deaths annually occur from diarrhoea caused by unclean drinking water.

It effects vulnerable populations especially. Constant re-infections from parasites in the water, usually found in faeces, can lead to delayed development in children under five as their immune systems struggle to fight off the infection.

The danger of some of these long-term effects on public health being spurred by fire and extreme weather events should be considered as the intensity and duration of bushfire seasons becomes more severe.

The public health risks associated with unclean water as a result of the bushfires will be complex to untangle. Taking data from other countries where it exists is likely to give policymakers an assessment of health risk that is not applicable to the Australian context, so there needs to be careful consideration when applying such data.

Even within bushfire affected communities health risks are likely to differ. For example, people connected to a town water supply may have a different risk profile compared to people who have private water supplies. Age, sex, and pre-existing health factors are likely to also play a part in any health response to unclean water.

It is important to realise that many public health impacts are likely to be delayed. These include physical health impacts associated with changes to water quality, and also the mental health implications of such disruptions. There is still no comprehensive understanding of the long-term health issues caused by disruption to drinking water supplies.

Unfortunately, trends in rainfall and temperatures across the country indicate that events like the 2019-20 bushfire season may become more common. Long-term exposure to inadequate drinking water for some communities, alongside less recovery time for water utilities between such events, could become a likely scenario going forward. In these circumstances, all we have is evidence the public will be at a higher risk of illness.

The situation demands more research on the long-term health effects of inadequate drinking water. This will help policymakers understand the types and magnitude of health impacts on different communities. Only then can they make good decisions about adaptation options that will help public health outcomes become more resilient to extreme climate events, decisions which will only become ever more important with each passing year.