How to Convert Salt Water to Fresh Water: Sun Science Project

You can purify water into a collection jar using a solar still.

A solar still converts salt water to fresh water, and is an important survival tool for someone lost at sea. It works by facilitating evaporation of the salt water by the sun, collecting the vapor and dispensing the purified water into a container. You can demonstrate the solar purification process behind these solar stills to children with a simple, fun experiment that just might come in handy some day. It is well-suited for science classes and summer camps.

Things You'll Need

• Large basin
• Small jar
• Rock
• Plastic wrap
• Rubber band or scotch tape

Instructions

1. Pour the salt water into the bottom of the basin, forming a thin layer of water. Place the collecting jar in the center of the basin.

2. Cover the opening of the basin with plastic wrap, and secure the plastic wrap with the rubber band or scotch tape. If using tape, use a plastic wrap just large enough to cover the opening to ensure the plastic wrap forms a tight seal.

3. Place the small rock on the plastic wrap, positioning it directly above the jar.

4. Place the still in the sun and wait several hours. The spot on the plastic wrap where the rock is placed will collect purified condensation and the water will drip into the jar.

Tips & Warnings

• Cover the rock with mud or water to cool the rock and facilitate rapid condensation.

References

• Education.com: Clean Water Using the Sun