Taking the pressure off our water supply

Less than 3% of all the world's water is fresh and less than a third of one per cent of this is available to humans.

The rest is beyond our reach, deep within the earth, or frozen in glaciers and polar ice caps. Put another way, if 100 litres represents the world's water, just over half a tablespoon of it is fresh water that we can use.

That's how precious fresh water is ...