The recent rain has given welcome relief to regional communities, but heavy rain after bushfires can impact water quality in home water tanks.
Deputy premier and minister responsible for disaster recovery John Barilaro said following bush fires, rainwater may be contaminated by debris, dead birds or animals, fire retardants, or large amounts of ash.
"If you have a rainwater tank, it's possible that it could be contaminated by debris, dead animals, ash or fire retardants," Mr Barilaro said.
"If the water looks, smells or tastes unusual you should use an alternate water supply, such as town water or bottled water, for drinking and preparing food or ice.
"Depending on the degree of contamination, the rainwater may still be suitable for other things like watering the garden, washing clothes or fighting fires."
Minister for water Melinda Pavey said staying informed was vital to ensuring the safety of drinking water from home tanks in bush fire affected towns.
"It is important to try to prevent water contamination by monitoring weather forecasts and sealing your water tank to avoid the first part of runoff after rain," Mrs Pavey said.
The NSW Government provided the following information:
Rainwater quality after bushfires
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 tank has been burnt by fire and/or the internal lining material is damaged
- the plumbing to or from the tank is damaged
- the water level has increased due to water bombing.
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.
Using contaminated 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. 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.
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Disinfection of rainwater
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 four to five per cent available chlorine) may be used. Add four drops of bleach to one 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.
After a bushfire
You may find that windblown ash, debris, dead animals or fire retardants have affected your rainwater tank when returning home after a bushfire.
If you haven't already done so, disconnect the down pipes from your tank. The first rainfall after the fire should be run to waste, if the roof has not been cleaned.
Clean your roof to remove ash and debris, if this can be done safely.
Check your roof and guttering for dead animals and remove if present.
Water testing is usually not necessary, as contamination is usually obvious.
If the water is contaminated the tank should be drained, cleaned and refilled. Working inside a tank can be very dangerous. Professional tank cleaners are available in some areas.
Filters and other water treatment equipment could be affected by debris. Refer to the manuals for your equipment or seek advice from the supplier on responding to problems.
After drinking water has been captured or delivered, flush taps in the property to bring through the new clean water from the tank.
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