Potential contaminants in rainwater after a bushfire

Using roof harvested rainwater held in domestic rainwater tanks is a common practice in Australia, particularly in rural areas. This rainwater might become contaminated with ash and other contaminants during or after a bushfire. Current advice from Australian Health Departments can include the recommendation that landholders drain their tanks after a bushfire, which can cause additional distress to landholders who have already been through a traumatic event. This study created artificially contaminated water, spiked with chemicals likely to be associated with bushfires, including chromated copper arsenate-treated timber ash and firefighting foam to determine the possibility of contamination. The authors also tested two readily available filter systems and found that they removed some but not all contaminants. The artificially created contaminated water fell within guidelines for nonpotable uses such as irrigation and stock watering. This suggests that advice to landholders should be that tank water following a bushfire is likely to be safe for use for purposes apart from drinking. Landholders should be encouraged to retain and use their water for recovery purposes, but not for potable use.