Rainwater Harvesting for Buildings: An Introduction

About this course.

Rainwater harvesting is the practice of collecting rain that falls on a surface — most commonly the roof of a building — and storing it so it can be used later, instead of letting it run to waste. In its simplest form it is a downpipe directed into a tank that supplies a garden; in a more developed form it is an engineered system that catches, filters, stores, pumps and, where needed, treats water for use inside the building. The idea is old and simple, but its value in Australia is significant, because water here is genuinely scarce and highly variable, and because managing the rain that falls on our buildings brings benefits both to the property owner and to the wider community.

Australia is the driest inhabited continent, with low and highly variable rainfall across much of the country and a long history of drought. Water security — having a reliable supply of water when it is needed — is therefore a serious, ongoing concern, and it is one that periodically tightens into water restrictions in towns and cities. Against that background, capturing the rain that falls freely on a building's roof and putting it to use is an obvious and practical response. A rainwater tank turns an intermittent resource into a stored one, smoothing out the gap between when rain falls and when water is needed, so that a garden can be watered, or a toilet flushed, from rain collected weeks earlier.