How much water can you harvest?
In 2019-20, the average amount of water used by households was 180,000 litres.*
Knowing how much rain water you can collect will help you decide on the size of tank. To use these handy calculators, you will need the average annual rainfall in your area and the total surface area feeding to your tank. From this information, you will then know what would be the maximum size tank to collect this water.
Remember though, you would generally not need a tank to capture all the annual rainfall as the rainfall throughout the year will top up your tank.
If you have access to clean groundwater or surface water, the availability of the water will determine your tank size.