Bushfires and water tanks

Bushfires generate large amounts of smoke, debris and ash. If you live in a bushfire-affected area, you need to be aware that your water tank could become contaminated. Sources of contamination can include dead animals, fire retardants, and debris or ash washed off the roof and into the tank when it rains.

Possible contaminants
Ash in itself should not make your drinking water unsafe. However, both ash and debris may contain chemicals that could be harmful if they get into your drinking water supply, while dead animals can make water unsafe to drink.

If there is debris and ash on your roof, the first flush of water will not be suitable for drinking. These contaminants may have already washed into your tank if you have been hosing your roof as part of your fire plan or if it has rained.

Fire retardants are chemicals used to decrease the spread or force of fires. They are often used by fire fighters on the ground and can also be dropped from aircrafts. Water contaminated with fire retardants may have high levels of ammonia and sulphate, making it smell unpleasant and taste salty. This water should not be drunk by humans or animals, but may be used for irrigation and fire-fighting purposes.

Install a first flush diverter
To protect your tank water in future, install a ‘first flush diverter’ between the roof and the tank. This prevents ash and other debris from contaminating the water. First flush diverters are available from most hardware stores and suppliers of rainwater tanks.

How to tell if your tank water is contaminated
The best guide is your knowledge of what your tank water usually looks and tastes like.

• If the water tastes or smells unusual, is cloudy or discoloured, or contains particles, you should assume it is contaminated. Do not use it for drinking, food preparation or making ice until the tank has been cleaned and refilled with new rainwater or clean water brought in by a water carter.
• If there is any doubt, assume the tank water is contaminated.
• You may choose to have the tank water tested before deciding whether to use it for drinking. A laboratory analyst can test a sample of tank water for chemical, microbiological and algae levels. To find a laboratory that can do this, look under Analysts in the business telephone directory.
• Water that is not suitable to drink may be used for other purposes such as fire fighting or watering the garden.
• Do not give contaminated water to animals to drink.

• Use the first flush diverter on your tank to divert any residual debris away from your drinking water storage.
• If you don’t have a first flush diverter, disconnect the inlet from the roof to the tank until the roof has been cleaned.
• When safe to do so, arrange to clean debris from the roof and gutters before it rains. Be careful to avoid injuring yourself.
• Dead birds or other small animals found in gutters should be removed using gloves and put in a plastic bag for disposal. Your local council’s Environmental Health Section can advise you about their disposal.
• To clean the tank, first remove any sludge. Then rinse or scrub the interior with a diluted household bleach solution. Use strictly according to the manufacturer’s instructions on the label.
• Do not climb inside the tank unless you can be sure you have good ventilation. Enclosed spaces can quickly become hazardous.

• Your doctor
• Your local council’s Environmental Health Section
• Laboratory analyst
• Water carting service
• Environmental Health Unit, Department of Human Services Tel. 1300 761 874

• If the water in your tank tastes or smells unusual, or is cloudy or discoloured or contains particles, assume it is contaminated.
• Do not use your tank water for drinking, food preparation or making ice until the tank has been cleaned and refilled with new rainwater or clean water brought in by a water carter.
• Water that is not suitable to drink may be used to fight fires or water the garden.

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