The benefits of rainwater harvesting:

When you think of a water tank you need to think on the larger scale of the system itself; the tank, downpipes, guttering, occupants of the home and the roof. You should try to install as large a tank as your home can afford, as the more rain saved for a dry day the better. The main benefit is that the rainwater falls just where we need it. pump it from an external source. There are also Government grants available in Victoria for water tanks connected to toilets or laundry.