For most people water is easily available, from rain, rivers, streams, lakes, ponds and wells.

However, it is important to remember that 20 per cent of the people in the world do not have access to safe drinking water.

We are using water all the time but it is never used up.

This is because the water on Earth is always being recycled in what is called the water cycle.

Heat from the Sun evaporates water from oceans, seas, lakes, rivers, ponds, puddles and other wet surfaces.

The water vapour rises into the atmosphere where it is eventually cooled and forms clouds.

From these clouds rain, hail, sleet or snow fall.

This water replenishes rivers and streams, which eventually flow back into the ocean or sea.

We are using the same water over and over again and it is even possible that some of the water you drank today was in Archimedes’ bath

 in ancient Greece about 2,200 years ago.