If you live in a bushfire-affected area your drinking water tank could have become contaminated from debris, ash, dead animals or fire retardants.
Some helpful tips for rainwater tanks:
If the water tastes, looks or smells unusual, do not drink it or give it to animals. Water from a river or creek should never be used for drinking or preparing food unless it has been properly treated. Water drawn from deep bores or wells should be safe to use.
Boil water for drinking purposes
Bring water to a rolling boil by heating water until a continuous and rapid stream of air bubble is produced from the bottom of a pan or kettle. Kettles with automatic shut off switches are suitable.
To guarantee no contamination you would be required to drain and clean the tank and allow it to refill with clean rainwater or fill with water purchased from a water carter.. If you cannot drain the tank, find alternative uses for the water other than food prep such as garden watering, fire-fighting, clothes washing, flushing toilets, or disinfect the water with chlorine. Remove the animal remains (empty the tank if you can) and disinfect tank water with chlorine.
How to disinfect your tank water using chlorine:
For every 1,000 litres of water in your tank you can safely add: 125 mL or 125 g of 4 per cent chlorine household bleach (avoid bleaches that contain detergents or perfumes), or 40 mL or 40 g of 12.5 per cent chlorine liquid swimming pool or dairy factory chlorine, or 8 mL or 8 g of 65 per cent granular 'swimming pool' chlorine.Note: one teaspoon is about five grams. After chlorinating, you should wait at least 24 hours before using the water to allow for microorganisms to be destroyed
If you believe your water source is contaminated by fire retardants, the requirements for disinfection are more stringent. You should not seek to disinfect the tank and should dispose of the contents. Before disinfecting and refilling from an authorised water carter. Boiling water does not remove fire retardants.