Calculating Your Average Rainfall & Ideal Tank Size
Knowing your average rainfall is vital if you want an appropriately-sized rainwater tank for your needs
Water consumption varies considerably, so it’s important to calculate your usage rather than relying on averages. Your water consumption habits is one of the key variables you need to consider when determining the size of your rainwater tank. It’s been estimated that a typical Australian family uses as much as 260,000 litres of water a year.
However, as consumption varies significantly from place to place, person to person and household to household, it’s important to calculate your own household’s water usage to more accurately determine just how much water you use.
Factors affecting water usage
There are many factors that will affect the volume of water your household uses.
Some key factors include:
- The number of people in your home
- Your property’s size and outdoor needs (garden irrigation, outdoor cleaning, swimming pool top-ups)
- Lifestyle factors (number/frequency of guests, shower/bath use, laundry and car washing habits)
- Size and efficiency of your water-using appliances (dishwashers, washing machines, shower heads)
- Your water conversation habits (such as if you partially or completely fill your washing machine drum before washing)
- Whether animals are kept on the property
(Adopting water wise habits is one way to lower your water usage without disrupting your lifestyle.)
Past water bills
If you live in an area supplied with mains water, you can use your past water bills to get an indication of your household’s water usage habits. If you have enough of them, you can use these bills to see how your water usage may have changed over time (for example, as your children have grown older) and whether there are any seasonal variations (for example, whether you use more water in summer than winter).
Calculating your average rainfall, ideal tank size and roof surface area
Knowing your average rainfall is vital if you want an appropriately-sized rainwater tank for your needs. There are many factors you need to consider when choosing your tank size. These factors include how much water you typically use around your property, the size of your roof and whether you will be relying solely on rainwater for your water needs. But before you worry about any of that, you need to know your average rainfall, as based on historic data.
Great Rain Harvesting starts with a great system.
Build yours by following the 4 Pillars of Rain Harvesting System Design.
Find out more
You may remember us as 
. We are the same people, same company – now with a new look. 
Interested in receiving news and product updates?