Drinking water during and after a disaster

Drinking water supplied by your local council or a water utility may not be available or safe to drink during or after a disaster.

Local councils and water utilities have an obligation to alert the public if they know or suspect the safety of the water has been compromised.

To check for updates on your water supply:

• check your council’s website and social media pages
• watch disaster coverage on the television
• listen to your local radio station.

Making drinking water safe

If your local council or water utility advises drinking the water might make you sick, they will require you to take certain actions before the water can be safely consumed. Your council or water utility may provide an alternate source of potable water (e.g. tanked drinking water), however the most common action required is a ‘boil water alert’.

Water should be brought to a boil and allowed to cool. It is safest to boil water using an electric kettle. If you have lost electric power water can be boiled, using a saucepan, on a gas stove, barbeque or portable gas cooker. Take care when boiling water as it can scald. Always take care when boiling in pots and pans, particularly if you have young children or vulnerable people in your household. The water should then be stored in clean, covered containers.

Once boiled water has cooled, it can be used for:

• drinking
• preparing baby formula
• hand washing
• preparing food and cooking
• brushing teeth
• bathing infants
• making ice.

You do not need boil water for toilet flushing and clothes washing.

Once your council or water utility advises the water is safe to consume, you should consider if taps were affected by floodwater. Remove any screens or aerators from affected taps and flush the water for a couple of minutes to remove any contaminated water. Clean the affected parts and tap with hot water and detergent.

Making tank water safe

Drinking water in rainwater tanks may not be safe to drink during or after a disaster.

Preparing tank water before a bushfire

Bushfires produce large amounts of smoke, ash and debris that can settle on roofs used to collect rainwater. Fire retardants and foaming agents used in fire-fighting activities may also be deposited on roofs. It is important that the pipes that direct the water from the roof to the rainwater tanks are disconnected to ensure your supplies of roof-harvested rainwater remain safe. The disconnection should be made as soon as the threat of a bushfire is apparent to prevent windblown debris entering the tank.

Tank water after a bushfire

If the rainwater tank has not already been disconnected from the collection pipes, disconnect or redirect the pipes as soon as it is safe to do so. Once this step has been completed clean the roof and gutters thoroughly. Cleaning the roof and the gutters with water that is known to be safe is likely to be the most effective way of removing ash and other contaminants that might be present (don’t use a pressure washer if you have an asbestos roof). The use of a mild detergent and may be required for residues that won’t wash off. Once the roof and gutters have been cleaned, the pipes that direct water to the tank can be reconnected. Ensure the first-flush device, if installed, is empty and in good working order.

If it has rained since the bushfire, and before the collection pipes have been disconnected, it is likely that ash and other contaminants will have flowed into the tank. In most cases, this will mean that the tank will need to be drained and cleaned before prior to collecting drinking water or personal hygiene. If the bushfire has damaged the integrity of the tank, it is likely that the tank will require draining and repair or replacement.

Tank water after a flood or severe weather event

Water from tanks should not be used for drinking or personal hygiene if the tank has been, or is suspected to have been, contaminated with flood water. Tank water should also not be used if connecting pipework has been damaged, or where flood water has been in contact with taps or connections within or outside the home. Stored tank water may continue to be used for toilet flushing and clean-up purposes. If rainwater contamination has occurred or is suspected, the town water supply should be used for all drinking and hygiene purposes.

Reinstating the tank water

If your tank has been inundated with flood waters, the water will have been contaminated and should be discarded. If you have an underground tank, you should not attempt to empty it while the surrounding ground is still saturated. Emptying water before the surrounding ground has dried out may result in damage to the tank and associated plumbing.

Once the tank has been emptied, the inside of the tank should be hosed out with clean water and sanitised. Any associated plumbing, guttering, downpipes and roof surfaces inundated by flood waters will also need to be cleaned and sanitised. A tank supplier will be able to advise on the best sanitation method depending upon the material the tank is constructed of. If cleaning of the tank requires entering the tank, it is recommended that a qualified, professional tank cleaner undertake this activity as working in a confined space is hazardous.

Cleaning agents that release hazardous fumes or adversely affect the water quality after cleaning should not be used.

After cleaning and sanitisation has taken place, the tank should be refilled with water from a source known to be safe and should be appropriately disinfected using enough chlorine to give an initial chlorine dose of 5 mg/L. The amount required will depend on what form of chlorine you use and how much water is in the tank.

Guidance on calculating the volume of your tank and on chlorine dosage can be found in the further information section below, however as a general rule:

• household bleach (four per cent concentration) — 125 mL or 125 g/1000 L
• liquid swimming pool chlorine (12.5 per cent concentration) — 40 mL or 40 g/1000 L
• granular swimming pool chlorine (70 per cent concentration) — 7 g/1000 L.

When using Chlorine, it is important to remember to adhere to the warnings, directions for use and safety precaution advice contained on the product label.

After adding, allow to stand for at least one hour (or overnight if possible).

Further information

• Call 13 HEALTH (13 43 25 84) at any time.
• Contact 13 QGOV (13 74 68) for your nearest Public Health Unit.

If you or anyone in your household is experiencing any health effects from contaminated drinking water, seek medical advice from your doctor.

Download the drinking water safety in a disaster factsheet (PDF 384 kB).