Rawabi

Rainwater can be harvested and used internally for the flushing of WCs and within washing machines, or externally for irrigation and vehicle washing. Collection from roofs is the standard method, however, surface water runoff from the hard landscaping could also be collected but would require additional treatment (oil separation) and filtration.

The rainwater yield is dependent on the average rainfall and the type and area of catchment. The rainfall in the region is concentrated around the winter months with very little rainfall from May to September. This variation in rainwater yield throughout the year results in limitations on a potential non-potable water supply from rainwater.

Oversized storage tanks would be needed to capture sufficient rainwater for a non–potable water supply to last through the summer months, although even with the oversized tanks a constant supply could not be guaranteed because of variations in rainfall levels and frequencies. Rainwater systems could support the water supply throughout the winter months with tanks designed for around 10-20 days storage based on the predicted average rainwater yields during the months with significant rainfall.