There are a number of rainwater calculators currently available which will make the decision process easier if you are in the market for a new rainwater tank.
Tankulator The Alternative Technology Association has developed a calculator to help you select the right tank size for your rainwater storage needs. Visit the Tankulator website to use the calculator and find out more information about installing a rainwater tank.
H2OmeCalc The Smart Water Fund, Arris Pty Ltd, and the savewater!® Alliance have developed an online calculator most cost effective and efficient way to use rainwater and greywater as additional water sources around the house and garden. Visit savewater.com.au to use the H2OmeCalc.
Area Calculator To help you decide what size rainwater tank you need, you will need to know your roof or catchment area. Visit the Google Map Developers' website to calculate your roof area by satelite view.
Rain Tank Calculator
This calculator provides a greenhouse gas and a water saving figure depending on whether you install a large, medium or small tank. Visit the Smart Approved WaterMark website to see what savings you could make.
iSaveH2O The Smart Approved Water Mark has developed a rainwater tank app for the iPhone: