Science Fair Projects

Desalinate Sea Water


The purpose of this experiment is to demonstrate how the solar system, specifically the water cycle, produces fresh drinking water through desalinate of sea water. I chose this problem because I wanted to show people about desalinate sea water. Basically we are trying to find out how the solar system produces fresh drinking water through desalinate of sea water. I hypothesize the solar system can produce desalinate sea water by evaporating and condensation.


Iodized Salt Bottled Drinking Water/Tap Water Heavy Ceramic Cup or Mug Large Glass Bowl Plastic Cling Wrap A Rock or Small Weight Sun
  • 1. Pour the drinking water into the cup or mug so that it's about 1 inch deep.

    2. Mix some of the salt into the water. Add enough so the water tastes salty. *If you drink some of the water, make sure to re-add water so it's at a depth of about 1 inch.

    3. Pour the salted water from the cup into the bowl.

    4. Rinse the cup and dry it, ensuring it's free of any salt residue.

    5. Place the cup in the center of the bowl.

    6. Cover the bowl top tightly with your plastic cling wrap. Ensure there are no open spots around the rim.

    7. Find a safe and clean place that gets lots of sunshine, such as on a window sill. Put the bowl down where it can get the most amount of sun.

    8. Place your rock or weight on top of the plastic wrap, right above the cup. The rock or weight should cause the plastic wrap to sag in the center above the cup. This step is essential to ensuring the waterfalls into the cup.

    9. Wait several hours.

    10. Water condensation should form on the underside of the plastic wrap. Where you have your rock / weight placed you should see drops of water formed and flowing downward slowly into your cup. Once the cup has some water in it (the will be a small amount) you can pull back the plastic wrap and remove the cup.

    11. Drink the water. It is pure and clean, which is free from any salt.

Planning the Procedure

Water vapors from inside the bowl as the sun warms the water, evaporating it. The plastic wrap acts as a form of greenhouse, trapping the vapor inside and causing the humidity to rise to 100%. The top of the plastic wrap is much cooler because it's in contact with outside air. When the humid air inside rises and touches the top of the plastic wrap (the cooler area), the water vapor condenses and forms water droplets on the under surface of the wrap. As time passes the water droplets around the plastic wrap grow larger and flow to the center of the wrap where the rock is. As the droplets join together, they grow heavier and eventually drop into the cup. The result is pure, clean, fresh drinking water that's devoid the salt.

Scientific explanation:

In conclusion I have learned that you can produce fresh drinking water from the solar system through desalination of water, by evaporating and condensation. Evaporating is from the sun. Condensation is from the water vapor.

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