Water Sustainability

There are about 1,385 million cubic kilometres (1 cubic kilometre equals 1 billion litres) of water in the world covering nearly three-quarters of the earth’s surface. We turn the tap on. Water comes out. Pull out the plug. Water disappears. It used to be easy to take water and sewerage systems for granted when you live in the city. However, Australia’s record drought and water restriction in most of the state capital cities has brought home the importance of conserving water.

The trouble with water is that even though most of the planet is covered with the stuff, over 97% is undrinkable salt water. A further 2% is fresh water trapped in icecaps and glaciers. More fresh water is locked too deep below the earth’s surface to be extracted. What remains is a tiny 0.003% of all the earth’s water as available fresh water in the forms of surface water (in lakes, reservoirs and dams, for example), accessible groundwater, soil moisture, water vapour, clouds and rain. With climate change looming, the prognosis for many parts of Australia is grim, with climate modelling data predicting less rainfall converting to flows into the catchment areas that supply us with drinking water. In other words, the new ‘normal’ is likely to be one with less rain where it’s needed.

We need to think of our fresh water resources as a bank account filled with water. We can only make withdrawals up to the rate that nature replaces the water through rainfall. We also have to account for our growing population so that our water needs are secured into the future. If we can’t live within our water means, then we have to investigate alternatives, such as energy– and greenhouse-intensive desalination plants. Dr Karl once described desalination as the process of converting salt water to fresh water by throwing money at it!