Before using H2OmeCalc
The aim of H2OmeCalc is to encourage the exploration of non-potable water supplies first if available (e.g. greywater and rainwater); and then meet the remaining demand from potable or drinking water sources (e.g. Mains water, bore water).
This approach assumes that mains water can be used as a backup, acknowledging that there are extreme weather situations where potable water should be utilised to ensure garden survival if significant water is saved through out the rest of the year by using rainwater or greywater (yearly water accounting).
In order to allow for rainfall variability and recognising that water restrictions may not allow potable water back up in dry years H2OmeCalc includes an allowance in the rainfall section to model both dry and wet years. For example, nominating 70–80% of average rainfall would indicate a fairly dry year, while 130-140% would model a very wet year. Nominating 100% of average rainfall is an average year.
Information that you will need to supply in order to use H2OmeCalc includes:
- Your town or suburb
- The number of toilets in your home and their water use per flush
- Type of washing machine in your home and the usage
- The different planting types and their areas of your garden
- A general description of plant water demands (high - fern, medium, low - cactus) planting density, degree of sun and wind exposure and depth of mulch of different areas of the garden
- Shower type, use, and average time for everyone in the household to take showers
- The area of roof from which rainwater is or will be collected from
- The volume and height of your rainwater tank
- Rainfall variation estimate. This section allows users to input their own prediction of future rainfall volumes they expect to receive in a year compared to the available data from between 1900-2000. For example, 70-80% of average rainfall would indicate a fairly dry year. If 130-140% is entered this would give you idea of very wet year. The figure that you put in here impacts on both the amount of rainfall captured and the amount of additional water that is required to supplement rainfall on your garden.
Some inputs use a simple scale with drop down menus rather than numerical input. For example the garden types are either turf or garden, and water demand, planting density and degree of sun and wind exposure are either high or medium or low. This information can be collected as you use H2OmeCalc or you can make a guesstimate and update the information at a later date. You will also need to decide what zones of the garden will use which water source.