Fun in the Sun

Build a Solar Still

The Sun is the source of all energy on our planet. Harness this energy by building a solar still to remove contaminants from water.


  • Large bowl
  • Small glass container that fits inside the large bowl
  • Plastic wrap
  • A small rock
  • Water
  • A contaminant, like dirt, salt or food colouring to add to the water

Let’s get to work!

  1. Add water to the large bowl, so that there is about 1 cm of water at the bottom.
  2. Add the contaminant of your choice to the water (in our photo we use blue food colouring) and mix it in.
  3. Place the smaller glass container in the centre of the larger bowl, sitting in the water.
  4. Loosely cover the top of the large bowl with plastic wrap. If needed, you can tape the plastic wrap to the sides of the bowl to help it stay in place.
  5. Place the small rock on the plastic wrap, so that it sits just above the small glass container in the middle.
  6. On a sunny day, put the whole setup outside in the sun.
  7. After 1 to 2 hours, clear water should accumulate in the smaller container. Depending on the time of year and the cloud cover, you may need to leave it out for longer.

Take note!

Do not drink the collected water. It may still contain small amounts of the contaminants.

What happened?

The plastic wrap allows sunlight into the larger bowl but prevents heat from escaping. This causes the water to heat up and evaporate, leaving the food colouring or any other contaminant behind. The clean water vapour condenses (becomes liquid again) as it hits the plastic wrap, gathers at the dip in the plastic wrap (created by the rock) and then drips into the smaller container.

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