Drinking water from a homemade desalination plant

How is drinking water obtained from salt water? Is it an easy or difficult process? You will be able to answer these questions with the experiment we propose.

Materials

• Water
• Salt
• A transparent bowl
• A stone or a heavy object
• Transparent kitchen paper

How to create a homemade desalination plant

1. Dissolve the salt in a bowl filled with water, stirring until completely dissolved.
2. Place an empty glass upside down inside the bowl.
3. Cover the bowl with transparent kitchen paper making sure it is completely sealed.
4. Place a stone or similar object in the centre of the plastic making sure that a small depression is created by the weight of the object.
5. Place the bowl in a sunny spot and leave it to stand for several hours.

What I will see

After time has passed, you will notice that with the effect of the sun, the water has evaporated and condemned itself in the depression created by the stone. You will see that the empty glass is now full of water, but now it is fresh water!

Explanation

This experiment aims to reproduce, on a smaller scale, what happens in the atmosphere with the action of the sun on seawater. The sun heats the water in the oceans, seas, and lakes in the same way as it has heated the saltwater in the bowl, causing the water to move from a solid to a gaseous state.

In the atmosphere, the water vapour rises to a higher altitude, giving rise to clouds. It is here that the condensed droplets gradually coalesce, eventually leading to precipitation, when gravity pulls the water back to Earth in liquid form. If the temperature is very low, this precipitation can occur in the form of snow or granite (the third state of water, solid).

In our home desalinator, we have used the bowl and the film to generate the first phase, creating a kind of greenhouse effect, and with the stone or heavy object, we have managed to reach the second phase of this process.

If you want to know more about desalination, take a look at these resources:

Desalination and its importance

Desalination techniques

Seawater desalination by nuclear energy

Benefits of nuclear desalination

Top nuclear desalination projects