Education

Think about all the times each day you use clean water, the day to day- you may not even realize. Clean drinking water washing the dishes, cleaning dirty clothes, taking a shower, boiling water for a pasta dinner. Now imagine your day without clean water. What would you drink? How would you cook? How would you bathe?

Did you know, you can harness the sun’s renewable energy to purify contaminated water? With the sun’s heat and the help of the water cycle, we can take dirty, undrinkable water and purify it through the use of a solar still.

A solar still, or solar filtration system, is a device that uses the sun’s heat to create condensation, which is collected for use as a clean water supply. Essentially, the sun supplies the energy needed to drive the water cycle (evaporation, condensation, precipitation) and in turn, usable water is created.

Experiment Materials
(1) Small glass or plastic container (to collect purified water; must fit inside larger container)
(1) Large glass or plastic container (to place contaminated water; must be large enough to house smaller container)
(1) Food coloring color, blue or any preferred color(8) oz. (or 1 cup) of water
(1) Piece of clear plastic wrap, large enough to cover your large container
(1) Rubber band, or alternatively tape
(1) Small rock
(1) Small, clean, heavy item like paperweight to hold small container if necessary

Step 1: The first thing you will need to do for this experiment is to pick a large container to fill with your contaminated water, and a smaller container to collect the purified drinking water. You need to make sure your smaller container will fit into the larger one with some room to spare on the top and sides.

Step 2: Fill your large container with a thin layer of water, approximately 1 inch deep.  Add a few drops of food coloring to your water to show it is no longer pure. The food coloring in this experiment is acting as our impurities and will be a way for us to visually understand the purification process.

Step 3: Place your smaller empty container in the middle of your larger container. If the container is trying to float away, place a clean heavy item, like a paperweight, inside to weigh the container down, or use a heavier container. The smaller container will act as the collection agent for our purified water. Make sure none of the water with food coloring gets inside your small container.

Step 4: Loosely place the plastic wrap on top of your large container making sure to cover the entire top. Let some of the plastic wrap fall over the sides of your large container so that you can seal everything tightly.

Step 5: Use a rubber band to secure the plastic wrap in place around the rim of your larger container. If your container is too big, use tape to hold the plastic wrap in place.

Step 6: Use a rock to create a dip in your plastic wrap right over your small container; this dip will cause the condensation that collects on your plastic wrap to roll down to the lowest point and drop into the container.

Step 7: Set your solar still outside in a very sunny spot making sure to check on it periodically to keep it in the best position to utilize the sun’s heat.

Step 8: Observe your solar still filtration system throughout the day to see how much water is collecting in your small cup. You may want to leave your still outside for multiple days to allow the sun to work its magic.