Solar Still

In a desert environment finding or producing water is a most important skill for survival. This is a technique for extracting water from the soil or from plants by condensation.

• Clear Plastic Wrap
• Cup or Container
• Green Plant Material (optional)

Energy from the sun is used to evaporate water from the soil, or green plants if available, which condenses on the plastic wrap and drips into the container.

Dig a hole small enough to cover with your plastic wrap. The more exposed surface there is on the sides of the hole, the faster water will evaporate, but the hole must be completely covered by the plastic wrap. If the hole is to deep the bottom will be shaded much of the time which reduces the efficiency of the still. Make sure the hole is just deep enough to leave about two or three inches above the top of the container.

While not necessary, adding plants will greatly speed up the evaporation process. I'm using a cactus here. The cactus has soft flesh full of water, so it works well for this purpose, but any leafy plant will work. Peeling off the skin or cutting it open allows the water to evaporate faster.

Place the container and the plants in the bottom of the hole, leaving the opening of the container unobstructed. You can add more plant material than pictured.

Stretch the plastic wrap over the hole and weight down the edge with dirt. Make sure you have an airtight seal. Pinning the corners down with sticks will help hold it in place. Finally place a pebble or some dirt directly over the container. This will ensure the water will collect inside the container.

The sun will heat up the interior, like a greenhouse, evaporating water out of the plants and soil. As the temperature inside of the hole exceeds the temperature outside, water will begin to condense on the cooler plastic and drip into the container.

By constructing several of these, and keeping them stocked with fresh plants, you can generate enough fresh water to survive.