Solar Stills

Overview: Solar stills use sunlight in order to evaporate dirty or salty water and then condense the water vapour to be collected. There are many models for this but which one is the most effective? Note: It is probably worth doing the Insulated container and the hand washing station before you do this experiment as the concepts can be combined in this one.

Task: You are to make a solar still that can produce clean water from dirty or salty water. Either as quickly as possible or the maximum possible in a set period of time.

Equipment Provided: Plastic bottles of various sizes, tin cans, plastic bags, plastic trays, string, tape, scissors, silvered crisp pockets, black paper , black ink

Health and Safety: You must carry out your own risk assessment (Rubbish Science accept no liability)  Note: Do NOT drink the ‘clean’ water you have produced ! Be careful cutting

Things you might need to know / Questions you might ask:

  • How can you make water evaporate quickly? 
  • How can you get water vapour to condense effectively?
  • How can you combine evaporation and condensation to make a system that works?
  • How much dirty water should you use? Does the volume or the surface area have the most effect?
  • Does making the water black affect its evaporation rate?
  • What do commercial solar stills look like? 
  • Can you use ideas that were learned in the hot water hand wash station and Insulated container to help with this task?

Prototyping: Design some systems to answer the questions above.

Modifications: Having seen others ideas is there anything you might want to change?

Prediction: How well do you think your solar still will work and why?

Do it: What results are you going to take? How will you record them. Where is the best place to site your still?

What happened?: Did your results support your prediction

Tell Someone: Explain what went well and what you think might be improved. Listen to their ideas and decide if they have value.

What did you learn? What do you know now that you didn’t know at the start of the investigation?

Extension/Modify/Do it again: What would you do differently?

Possible Model – How can you optimise the design?