Water sources: Rainwater harvesting

Rainwater tank in garden

As we continue looking at water sources, this week we turn to a water source that many Australians are using, and it can be as close as your own backyard; rainwater!

What is rainwater harvesting?

Rainwater harvesting uses water flowing from the roofs of buildings and stores it for later use. Most people just think about the rainwater tank but the best outcomes are achieved if you think about the whole rainwater harvesting system including the roof, gutters, downpipes, occupants, tanks, pumps and the wider environment.

What can rainwater be used for?

Modern homes use rainwater harvesting systems to flush toilets, fill washing machines, fill swimming pools, water the garden, other outdoor uses and for non-chlorinated drinking water. Over 2 million Australians drink rainwater every day but because it can be potentially contaminated from the air and roof you have to be sensible about how you use it. Ground-breaking research from Dr Peter Coombes demonstrates that there is a biological treatment train occurring within rainwater tanks that can be utilised to maintain good quality water.

rainwater tank behind kangaroo paws

How is rainwater used?

The traditional corrugated iron water tank is an Aussie icon, and Australians design some of the best rainwater harvesting systems in the world. Over one third of all Australian households (34% of households that are suitable for tanks) have a rainwater tank. Each tank can save up to 100,000 litres each year or about half the average household consumption. Every Scout Den in Australia uses a rainwater tank to flush their toilets and most Bunnings have some enormous tanks as part of their retail stores. Queensland has the highest proportion of residential water tanks, while Western Australia has the least.

What are some of the benefits of rainwater harvesting?

The critical benefit of rainwater is that it falls right where we need it. Rainwater for your garden does not require pipes, energy and treatment plants to transport it from a dam in the mountains to your washing machine or your toilet. The main factors in how much water you save is not just the size of the tank, both the number of uses (such as washing machine, garden, toilet) and the area of the roof connected to the tank are more important. It is recommended that most houses are best suited for tanks larger than 2000 litres.

In the following video, Colin Nash, Chairman of the Rainwater Harvesting Association of Australia, shares some more about rainwater harvesting.

What are some of the issues with rainwater harvesting?

CSIRO research shows that while rainwater tanks are very popular, about 30% of us are not sure how to maintain them. Simple but important problems include broken connections, leaves in gutters, pumps and diverters not working properly and mosquitoes.

Some websites that can help you include:

Do you own a rainwater tank? We would like to hear your story!