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Make dirty water pure and drinkable with evaporation & condensation

Suitable For

Grade 7



Time Required

 <1 Week



What’s it about?

Have you ever wondered what you would do if you got lost in a desert without any drinking water? This is a very scary thought indeed, but there is a way that you could be saved!

In the following science experiment you will learn how dirty water can be purified, by using only a container, plastic sheets and a few rocks:

Topics covered

Evaporation, Condensation, Water vapour

What will I need?


Procedure (Method)

Unfortunately, this section is only available in the e-book version of the project.

How does it work?

Unfortunately, this section is only available in the e-book version of the project.

The two processes responsible for purifying the water in this science experiment are: Evaporation and Condensation. The sun’s heat lets the water in the hole turn into very tiny droplets ‘gas’ which rise up into the air. This process is called ‘evaporation’ and the droplets are called ‘water vapour’. The plastic cover over the hole prevents the water vapour from escaping into the air and the water condensates against the bottom of the plastic sheet. The small stone in the centre of the sheet forms a ‘drip’ over the empty container and the ‘cleaned’ condensate water is collected in the container.

When water vapour is formed during evaporation, minerals like salt and other waste substances that were dissolved in the water are left behind in the hole. When water vapour condenses to become water again, it is relatively pure.

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