You can calculate the amount of water you can collect from your roof by using this simple formula.

Roof Area

Length (Metres) X Width (Metres) = Area (Square Metres)

(12 Metres X 10 Metres = 120 Square Metres)

Catchment

Perth Average Rainfall = 800mm or 0.8 Metres

Square Metres X 0.8 X 1000 = Litres Per Year

(120 X 0.8 X 1000 = 96,000 Litres Per Year)

~ These calculations should only be used as a rough guide ~