How to Make a Solar Still to Purify Water

How to Make a Solar Still to Purify WaterA solar still uses the power of the sun to purify water. The sun's heat evaporates water, and the vapor leaves contamination behind. Once the water vapor hits the top of the solar still, it condensates and slides down the lid into a collection basin. The U.S. Federal Emergency Management Agency says that a solar still is one way to purify water. A still is easy to make and good for use in a backcountry emergency.


Difficulty: Easy

Things You’ll Need:
  • Shovel
  • Water bottle
  • Sheet of plastic
  • Rock
Step 1
Select a damp place open to the sunlight. A damp location generates more purified water, so find a spot that water runs into. Dry streambeds, bottoms of hills and places near water sources make good locations.
Step 2
Dig a 3-foot-deep hole. You want to dig into moist soil, because the moisture from the ground will become the potable water. Add vegetation, contaminated water or urine to the hole to add moisture. Remember, a solar still purifies any water; so even urine will be drinkable.
Step 3
Place your water bottle into the center of the hole. To support the bottle upright, you can push dirt around its base.
Step 4
Cover the hole with a sheet of plastic. Seal the edges of the plastic sheet with dirt and rocks. Make sure the plastic is taut and the seal airtight. Place a rock in the center of the plastic and over the bottle. The sheeting should bend to a point over the bottle. When the moisture evaporates, it condensates against the plastic. The condensation slides toward the rock and drips into the bottle.
Step 5
Wait two hours. FEMA says a solar still will purify one quart of water in two hours. Drink your purified water and reset the still to make more.

Tips & Warnings

If you have a source of water and need to purify it, substitute a big bowl in place of a hole in the ground. Weigh your bottle down in the center of the bowl using a rock.
In a pinch, you can use a rain fly, ground cloth or tarp in place of a sheet of plastic.
For more water, use a pot from your cook set instead of the water bottle.

Article Written By Bryan Hansel

Bryan Hansel is a freelance photographer and kayaking guide who began writing in 1993. His outdoors articles appear on various websites. Hansel holds a Bachelor of Arts in English and religion from the University of Iowa.

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