This fact sheet provides information about what to do to protect your rainwater supply before and after a bushfire.
Rainwater may be contaminated by debris, dead birds or animals, fire retardants, or large amounts of ash.
The water may also be contaminated if:
The presence of ash and debris in rainwater is unlikely to be a health risk, but could affect the appearance and taste. Fire retardants currently used in Australia are of low toxicity, but may also affect the appearance and taste of rainwater.
If you are concerned that your rainwater tastes, looks or smells unusual, or you suspect your rainwater has been contaminated, an alternative safe water supply, such as bottled water, should be used for drinking, preparing food or ice, cleaning teeth and given to animals until your tank can be cleaned and refilled.
Depending on the degree of contamination, the rainwater may be suitable for toilet flushing, garden watering, washing clothes, fire-fighting or washing down surfaces.
In an emergency, when no other drinking water is available, rainwater can be disinfected by boiling or using household bleach (see below). This may not improve the appearance or taste of the water.
Using any rainwater contaminated with ash or other debris to fill swimming pools or in evaporative air conditioners may clog filters and pumps. Contact the air conditioner, filter or pump manufacturer for advice.
Rainwater can be disinfected by bringing to a rolling boil. A kettle with an automatic shut off switch can do this. Leave the water to cool before drinking.
If you cannot boil the water, unscented household bleach (containing 4% – 5% available chlorine) may be used. Add 4 drops of bleach to 1 litre of contaminated rainwater, mix well, and allow to stand for 30 minutes before use.
You should be able to smell the chlorine faintly 30 minutes after treating the water. If you can’t, you may need to add a similar amount of bleach again.