Overview
Rainwater is water harvested directly from roof runoff from domestic or commercial buildings and captured in rainwater tanks.
Availability
Rainwater availability is seasonal. The climate in Perth has large variations in rainfall that is high in winter when watering demand is low and low in summer when demand is high. To optimise the full potential of rainwater as a water source (in Perth) the rainwater system should be plumbed into the building for non-drinking purposes, such as in laundries and toilets.
On average, a roof area of 100m2 (approximately 50 per cent of an average house in Perth) can collect about 50 000 litres of water a year when plumbed for internal and external use. With an appropriately sized rainwater tank this could supply up to 20 percent of a household's water needs.
Water Corporation's Waterwise Calculator can help calculate domestic water usage.