Water - a precious resource

Source: Image courtesy of NASA

Do you know that the Earth looks like a giant ever-changing bluish marble in space?

That's because water covers 70 per cent of this planet, giving it its overall bluish colour from space.

Water forms the oceans and polar icecaps, and exists as clouds, rain, rivers, lakes, seas and ice.

It doesn't take much to realise that water is a very important part of our planet.

Water is one of the few substances that occurs on Earth naturally in three different forms; as a gas (steam or water vapour), a liquid (water) and as a solid (ice).

A simple molecule of water is made up of two hydrogen atoms and one oxygen atom (H20). Pure water is tasteless, odourless, and nearly colourless.

All known life on earth requires water to live. Although water is abundant, up to 97 per cent is salty and undrinkable, most stored in the world's seas and oceans. Only around one to two per cent of water is fresh and available for drinking by humans, plants and animals.

Because there is a limited amount of fresh water on earth that humans can use, it's very important that humans use fresh water thoughtfully.

The good news is that the earth's fresh water supplies are constantly refreshed through a natural process we call the water cycle - our planet's way of recycling water. Because of the wonders of the water cycle, water is described as a renewable resource.

How do we measure quantities of water?