Bushfires and drinking water safety

Bushfires and drinking water safety
By: Brendan Guiney, Water Directorate

With many Council areas in NSW affected by bushfires and 2019 being Australia's hottest and driest on record, unfortunately local water utilities in NSW cannot afford to rest. Rainfall is likely to result in increased contaminants in catchment runoff which will present challenges to the treatment of drinking water.

Water quality experts have predicted potential impacts to water quality. In this article from UNSW's Professor Stuart Khan he says, “Impacts to catchments from bushfires and subsequent erosion can have long-lasting effects, potentially worsening untreated drinking water quality for many years.” Professor Khan has also previously collaborated to prepare guidance to Identify and assess the water quality risks from extreme events, freely available on the Water Research Australia publications area of their website.

The NSW Government has recently called on NSW local water utilities to be prepared to increase water quality monitoring and optimise treatment processes to ensure drinking water quality continues to be managed according to the Australian Drinking Water Guidelines.  

NSW Local water utilities should contact their Regional Manager for technical assistance and contingency planning, but most importantly must consult on their drinking water safety issues with their local Public Health Unit at NSW Health. With regard to private water supplies, NSW Health has also provided advice on rainwater tanks and bushfire as well as fire retardants. Further advice and support is available for Councils from their NSW Public Health Unit. 

DPIE's Science Division has kindly shared their hillslope erosion risk data, including updated maps for different scenarios of fire severity (see the Members Area of the website, under 'Uploaded by Members') . The datasets are available for download at: https://datasets.seed.nsw.gov.au/dataset/modelled-hillslope-erosion-over-new-south-wales.

The University of NSW has kindly supplied a number of case studies and research projects on this subject for local water utilities to access they are also available in the Members Area of our website. CSIRO has also produced a useful blog on the subject: https://blog.csiro.au/the-relief-of-rain-after-bushfires/.  Thanks also to Bruce Murray of CWT for sharing the attached paper on managing water quality following bushfires. The paper suggests actions that need to be taken immediately, as well as in the short to medium term and long term. CWT has had past experience assisting councils following bushfires. We are also grateful for the assistance of the Water Services Association of Australia in making a number of bushfire recovery case studies available

Further information is also available on practical measures for managing post-fire soil erosion. The documents below were prepared as part of the PhD research project on the impact that erosion of sediment after bushfires has on the quality of drinking water in reservoirs:

Fire Note: Protecting our Water Reservoirs with Sediment Traps
Poster: Managing post-fire soil erosion in the Mount Lofty Ranges, South Australia