Canberra’s average rainfall is around 629 mm a year. The pattern is quite interesting, with more rain falling during the 6 hottest months than during winter.
For your information, here is the official Bureau of Meteorology map showing average annual rainfall (in mm) of Canberra and areas throughout New South Wales, as well as a chart breaking down Canberra’s average rainfall by month.
How To Harvest Your Rainwater (and calculate your savings)
Throughout the country, water truly is the most precious resource we have, and it’s for that reason that so many clever Australians are setting up simple rainwater harvesting systems at their residences.
In these systems, roof guttering collects water runoff and directs it to water tanks. From that point, the stored water can be used to clean, irrigate the garden, wash clothes, or even filtered for potable household use.
Just how much water can you collect from your roof?
Here’s how to calculate it:
Number of square metres of roof X the number of millimetres of rainfall = litres harvested
If you have 150 square metres of roof, and the average Canberra rainfall is 629 mm per year, then you could collect over 94,350 litres a year (150 x 629). And just a 10 mm rainfall would yield 1500 litres! In both cases, it’s safest to subtract 10% to allow for absorbtion, evaporation etc.