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Perth Rainfall


Perth’s average rainfall is around 790 mm. a year. The pattern is for high rainfalls from May to August- almost 70% of the year’s total rain in four months.

Here’s how to calculate how much water you can collect from your roof. Take the number of square metres of roof, muliply by the number of millimetres of rainfall, to give the number of litres. e.g. If you have 150 square metres of roof, and the average Perth rainfall is 790mm, then you could collect over 110,000 litres a year.

If you live in Perth (or elsewhere in Western Australia), we’d like to help you with your water tank requirements. Learn more at our Perth Water Tanks page.