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Water as a Precious Resource

People and Water
The Water Cycle

All living things need water. Water is a limited resource and needs to be managed well.

Water water everywhere...

We can’t live without water. If you look at a map of the world you will see that water covers much of our planet. Most of our water is seawater. There is freshwater in ponds, lakes, streams and rivers. Freshwater is also found under the ground and as vapour in the air. Clouds form from this vapour and water falls back down to Earth as rain, sleet, snow or hail.

Oceans of water

There is a lot of water all around us but most of this is not freshwater. Sea water has too much salt in it for us to drink. Most of the water that falls back to Earth becomes runoff. It travels some distance over land before making its way back to the sea. As it travels over the land, the water picks up salts and minerals from the rocks and soil and washes them into the ocean. That is why ocean water is so salty.


About 97% of Earth’s water is salt water. That leaves only about 3% that is freshwater. We can only use about a third of this freshwater. The rest is frozen solid in glaciers, in the snow on high mountaintops and in the polar ice caps.

The freshwater we use comes from surface water and groundwater. Surface water is water we can see in ponds, rivers, lakes and streams. Groundwater is water that seeps down into the ground and collects in the spaces between rocks and soil underground.

Protecting water

It is important to protect our water supplies from pollution. Once the water becomes polluted, it can be hard or even impossible to clean.

Plants and animals also rely on freshwater. Streams, rivers and lakes are home to many types of aquatic plants, fish, insects and birds. Some of these organisms need very pure freshwater.

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Nearly three quarters of the Earth's surface is water so it is often called the Blue Planet. Image: NASA: Harrison Schmitt & Ron Evans.

What proportion of Earth's water is drinkable? Image: UNESCO.

Only a very small proportion of the Earth's water is drinkable. Why is this? Image: Shelley Hersey, LEARNZ.

Water vapour is invisible and can only be seen when it cools and condenses into clouds or water droplets on cold surfaces. Image: Shelley Hersey, LEARNZ.

About 90 percent of the freshwater on Earth is frozen. Image: Shelley Hersey, LEARNZ.

People and Water
The Water Cycle