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Desalination Experiment for Kids

Roughly 71 percent of the earth's surface is covered by water and only about 3 percent of that water is fresh. High concentrations of dissolved salts in seas and oceans render these waters unfit for humans to drink; however, there are several desalination techniques that can make this salty water fresh. Even children can apply these techniques when doing science experiments.

Grow Light
- Pour two cups of water into a bowl or basin. Completely dissolve 2 tablespoons of salt and record observations of the solution. Place a tripod (made by fastening three pieces of wood together) over the bowl center. Cover the tripod with clear plastic wrap and secure the sides with tape or elastic bands. Make sure each side is wrinkle-free. Beneath each tripod corner, position a smaller collecting cup. Shine a grow light one foot above the set-up for an hour. Record what happens as condensation of salt water takes place. Taste and smell the collected water in the collecting cups and record the results.
Freeze and Strain
- Dissolve 2 tablespoons of salt and three drops of food coloring in 2 cups of distilled water. Record the changes that happened and pour the mixture into a shallow container. Place the container inside the freezer for about three hours or more, until it has settled into a snowy thickness. Put a clean sieve over a large container. Dispense the slush into the sieve and allow it to trickle down into the larger container for about 20 minutes. Observe both the mixture left in the sieve and that in the larger container.
Solar Powered
- Lay a 5-liter water bottle on its side and saw off the top side. Punch a small hole large enough for a flexible straw to go through on the adjacent side. Connect one end of the straw to a plastic collection cup. Position the cup in the middle of the bottle's open top side. Use aluminum foil to cover the bottom and back side of the bottle. Pour previously boiled water with dissolved salt into the cup. Seal the top side with clear plastic wrap, allowing a little sag at the center with a rock or a coin. Connect the other end of the straw to a plastic cup covered with clear wrap outside the bottle. Place the set-up under the sun. Observe the condensed water in the receiving cup outside the bottle.
Reverse Osmosis
- Take two pieces of 2-liter soda bottles and paint one black. Dissolve a half cup of salt in 2 cups of water and note down the degree of saltiness. Pour the salt solution into the black bottle. Join the two bottles together with a flexible straw or a piece of plastic tubing. Secure the straw or tubing with duct tape. Place the set-up in direct sunlight, making sure to position the black bottle higher than the clear one. Leave the set-up for some time. Take the condensate and test it for saltiness in contrast with the original solution.

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