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H2OmeCalc The simple greywater and rainwater calculator

Use H2OmeCalc to assess the most cost effective and efficient way to use greywater and rainwater as additional water sources around the house and garden.

To use H2OmeCalc you will need:

  • some basic information about the appliances in your home that use water (e.g. washing machine and toilets)
  • details of your roof and garden areas
  • the type of plants/garden you have

A list of information you should have available is provided in Before using H2OmeCalc. Typical values for Melbourne are provided as a start point and include average rainfall and evaporation data from the recent climate statistics (source: Australian Bureau of Meteorology).

Once you input your current situation into H2OmeCalc you have the ability to change various aspects of your model to see the impact that changes have on your choice of water-using appliances, your garden design, your alternative water source options and your budget. To help you get the most out of H2OmeCalc, questions you may like to consider have been provided in Using H2OmeCalc.


Disclaimer – This is a simple decision tool designed to give estimates for comparative purposes. It is necessary for the householder to get quotations and make their own decision based on the value they place on their garden etc. More information on the development of H2OmeCalc and the assumptions used in the calculations can be the "Background and assumptions" section of the website.