Rainwater tank contamination
Water in rainwater tanks may be contaminated with floodwater, debris, or bacteria.
If there is a risk your rainwater tank has been contaminated by floodwater, do not use the water for drinking or
cooking.
The tank will need to be emptied, cleaned and sanitised before refilling. Seek advice on how best to do so.
Drink and cook with bottled or boiled water until the tank can be confirmed as safe.
How to know if your rainwater tank is contaminated
Assume the water in your tank is contaminated if:
- you think the tank roof was covered by floodwater
- there are dead animals on your roof, gutters, or in your tank
- the plumbing to or from the tank is damaged
- the water is cloudy, tastes or smells unusual, or has an unusual colour
- the water contains debris or mosquitoes.
You can test bacteria levels in the rainwater by contacting your local government environmental health services.
Alternatively, you can test your water by contacting a NATA-accredited laboratory and ask for a 'Standard drinking
water test for your drinking water supply'.
Electrical safety
If you think your tank's pump or electrical equipment has been impacted by floodwater, you need to have it inspected
and declared fit for use by a licensed electrician before reusing pumps or maintaining the tank.
Emptying, cleaning and sanitising a rainwater tank
- If you have an underground tank, do not empty the tank while the ground is still flooded as it may damage the
tank walls and plumbing.
- Once the tank has been emptied, the inside of the tank should be hosed out with clean water to remove soil and
debris.
- Cleaning large tanks can be a safety risk. Seek advice from a qualified professional tank cleaner to clean
inside your tank.
- Following cleaning, sanitise the tank. Ask your tank supplier for the best sanitation method based on the
material the tank is made of.
- Any plumbing, guttering, downpipes and roof surfaces connected to a tank that has been flooded will also need to
be cleaned and sanitised.
Refilling a rainwater tank
When refilling a tank with water from a commercial water carting company, make sure that the carting company:
Read Water tanks on your property for details on refilling and disinfecting rainwater tanks.
Using non-potable water
Water that may not be safe to drink may be okay for showering, bathing and personal hygiene. It is important to have
clean and safe water source personal hygiene.
Tips to keep yourself healthy include:
- Keep hands clean to help prevent the spread of germs. Wash hands with soap or sanitiser, and water that has been
boiled or disinfected.
- Ensure your non-drinking water source is safe for bathing and showering. Be careful not to swallow any water or
get it in your eyes or up your nose. If you are unsure that your non-drinking water is safe to use for washing
yourself, check with local government or the Department of Health.
- Only use drinking water to brush your teeth.
- Only use drinking water and soap to wash open wounds. Cover with a waterproof bandage and if a wound becomes
red, swollen or oozes, get immediate medical care.
- Do not bathe in water that may be contaminated with sewage or toxic chemicals, or in rivers, streams, or lakes
that are contaminated by floodwater, sewage, or animal waste.
- For contact lens hygiene (use and storage) follow the guidance on Acanthamoeba and contact lens use.
- For nasal irrigation hygiene, follow the guidance on Nasal irrigation - is it safe?
Mosquito breeding
After flooding, mosquitoes may breed in rainwater tanks as well as other vessels, containers, equipment or debris
that may be holding water.
To prevent mosquitoes breeding in your rainwater tank, replace or repair insect screening and ensure the tank is
adequately sealed to prevent further access for mosquitoes. If this cannot be achieved or if the water is
contaminated, drain the tank as soon as possible.
Empty and remove or cover any other containers and equipment on your property that is holding water from rainfall or
the flood.
Read Water tanks on your property for other ways to prevent mosquito breeding.
Using contaminated rainwater
If a water tank has been contaminated by floodwater, the water can be used to:
- flush toilets
- water the garden
- wash clothes (providing it will not stain clothes)
- wash cars
- fight fires.
Do not use rainwater contaminated with debris to fill swimming pools or evaporative air conditioners because the
debris in the water may clog filters and pumps. Contact the air conditioner, filter or pump manufacturer for advice.
Do not use contaminated water for drinking, cooking, washing your face or cleaning skin wounds.
Bore water for drinking
Floodwater may contaminate a drinking water bore system or water storage tank.
If floodwater is suspected to enter the bore casing, the bore water is likely to be contaminated. Do not drink or use this water for cooking, washing your face or cleaning skin wounds.
If you are not sure if the bore has been inundated with floodwater, it is recommended the water is tested to confirm it is safe.
Drink and cook with bottled water.
Drinking water drawn from deep bores where flood waters have not entered the bore casing may be safe to use, though may safest to check.
Following flooding, disinfect the water from the bore pump to the storage tank by following the Emergency treatment of drinking water supplies. Seek specialist advice if required.
If your drinking water tank is supplied by a bore, the same steps to remediate the tank should be followed as those listed for rainwater tanks above.
Bore water – garden purposes
After flooding, do not use garden bore water for drinking, cooking, washing your face or cleaning skin wounds.
You may use bore water to wash clothes or for irrigation.
More information