Rain harvesting during drought may seem like a contradiction- in times of drought there isn’t any rain to harvest, we hear you say- but hear us out, drought means extended period of below average rainfall, not no rainfall at all (well, at least not if you live on or near the coast, like us and the majority of Australians). And whilst this may mean a lot less rainfall than usual, a rain harvesting system such as a rainwater tank can yield a lot from a little. We’ll show you just how much, using Wollongong’s recent rainfall as an example.
In the last 7 days, from March 15 to March 21 inclusive, the Weatherzone station for Wollongong, which is located at Bellambi Point, recorded a total of 157 mm of rain. Now stick with us because there’s a bit of math involved, but firstly, for the purpose of simplicity, we are going to round 157 mm to 150 mm.
Since one millimetre of rain over one square metre equals 1 litre, we can multiply roof size by rainfall in millimetres and calculate how many litres that would have yielded. On an average 3 bedroom house, with a roof size of 150 square metres, 150mm of rain equals 22,500 litres. On an average 4 bedroom house with a roof size of 200 square metres, 150mm of rain equals 30,000 litres. On an average 5 bedroom house with a roof size of 300 square metres, 150mm of rain equals 45,000 litres. On everyone’s roof in the short space of a week! That’s a lot of water when the entire state of NSW is in drought.
The very concept of rain harvesting has sustainability at its core. That is, catching rain when its available, and storing it for later use. In doing so, you draw less from mains water and from the dams that are lowering every day, and in turn, you reduce your water bill. Not only that, you will be less affected by any water restrictions that may need to be imposed. So even if we only get that 150mm of rain 4 or 5 times over in a year when we would usually get it 10 times, catching it and storing it in a rainwater tank provides you with the freedom to continue watering your garden and washing the car until the next rainfall, rather than being restricted to withered plants, crusty lawns and dusty cars!
Of course, if it rained every day, water wouldn’t be so precious. But Australia is the driest inhabited continent, with NSW in the grip of severe drought and the desalination plant in Sydney up and running at significant cost. That’s why its so important to make the most of every drop that falls for free from the sky.