Friday, February 19, 2010

Solar Still.......

The Solar Still

I was not getting any cooperation from the weather getting this week's forum together.  I made a Solar Still, actually two different types, and put them outside to produce clean, clear water.  Well, the sun did not come out for long and the still didn't produce the way I had hoped it would.  I will try again on a sunny day.  We did have a great turn out of people and much participation in the forum this week.  It was Great!!!  Thanks to all that attended, especially the newcomers from the 6th and 9th wards.  We even had a visitor from Layton!!!  Everyone is welcome to come. 
The solar still works on the principal of condensation, which is pure water, dripping into a container.  The water that comes from the condensation is distilled water and pure to drink.  So use your imagination to make what ever type of still you can imgine with the materials you have.  I used a dark colored cleaned out root beer bottle.  It was dark in color so it heated the water inside faster to make the condensation faster.  I attached a tube to that bottle and ran the tube into another bottle placed at a lower level so the condensaton would run into it.  It was easy!  The other one was a large bowl with dirty water inside. Another smaller bowl was placed in the middle of the large bowl.  Plastic was placed over the top tightly to allow the condensation to form.  In the middle of the bowl above the smaller bowl, I placed a rock to create a lower spot on the plastic so that the condensation would run to the low spot and drip into the smaller bowl.  It worked but I didn't get as much pure water as I hoped, because of the lack of sun.   So use your imgination to create a still and let us know what you did and how it worked.
Here are some instructions for a serious solar still.  See the picture above.

Solar Water Distiller

Solar Stills operate on the same principles that produce rainfall. The sun is allowed into and trapped in the Still. The high temperatures produced destroy all pathogens. The water evaporates, and in this process, only pure water vapor rises in the Still, only to condense on the glass. The glass is sloped to the south, and the condensed water runs down the glass and is collected in a trough. The water is allowed out of the collector through silicone tubing, and is collected in 5 gallon glass jugs. There are no moving parts in the solar still, and only the sun's energy is required for operation.

The design of the our Solar Still began with many hours spent researching previous designs, successes and failures. Our goal for the Still project was to design and develop plans for a Still which could be replicated using "off the shelf" materials.

We designed a still which is easy to replicate, using standard building materials, of which 95% are available "off the shelf". The exterior materials were chosen for their ability to withstand our desert climate with minimal maintenance. The still produces an average of 3 gallons per day in the summer months. Winter production is expected to be 1/2 that amount. The Solar Still can utilize a standard size patio glass replacement, 34"X76".

Brackish water is carefully placed inside Solar Still via an inlet near the base of the Still. As sunlight warms the black silicone bottom and heat is transferred to the water, the top of the water evaporates on to the inside of the glass cover, which is tilted toward the fresh water drain. approximately 8 square feet (of glass cover) will distill around 1 gallon of water per day, over five hours of full sunlight.

The most important elements of the design are the sealing of the base with black, high temperature silicone rubber; (spread it on with a Bondo squeegee) and creating a good seal between the glass cover and the bottom of the box.

The Solar Basin Still

The Still is filled each morning or evening, and the day's production is collected at that time. The Still will continue to produce after sundown as the water is still very hot. The Still is over filled each day to flush out sediment. The over flow water can be used for irrigation. The only maintenance is to clean the glass occasionally.

A Large Solar Distiller Array!

Many stills put together and dripping into a large container of fresh, pure water!

Emergency Survival Tool

Fortunately, there is an emergency survival technique for gathering water from our driest deserts during their most brutal seasons. It is commonly known as the Solar Still. One of the most significant survival tools created in the last 40 years. the Solar Still was developed by two physicians working for the U.S. Department of Agriculture. Results of extensive testing in the Arizona deserts by the U.S. Air Force proved that when properly assembled, the still can save your life.

The Solar Still functions under the general principle of the "greenhouse effect". Solar energy heats the ground by passing through a clear plastic barrier. Moisture from the soil then evaporates, rises and condenses on the underside of the plastic barrier above.

The still also has the ability to purify tainted water. In fact, it condenses pure water from just about anything. Even urine will produce clean, drinkable water. (CAUTION: One fluid never to be used is radiator fluid, as its toxins will vaporize and poison the water.)


There are only 2 essential components to constructing the Solar Still -- a container to catch the water and a 6 x 6-footsheet of clear plastic. A shovel or trowel, a length of plastic tube and tape are all optional.

The container can be a collapsible cup, an empty plastic bottle, a small cooking pot or just about anything with a large enough opening to catch falling drops of water. In a pinch, even tin foil or a sandwich bag can be fashioned into a workable receptacle.

The sheet of clear plastic can be a ground cloth used under tents when backpacking or a thin painting drop cloth. Both work well as long as there are no tears or holes. This is the one item that should be carried at all times, since there is no natural substitute out in the boonies. I keep a 6 x 12-foot plastic drop cloth taped inside my daypack, large enough to make 2 stills if necessary. Some desert rats like to keep their plastic sheets folded inside a hip sack or as part of their first-aid kits.

A 6-foot length of flexible plastic tubing, similar to the kind used in fish tanks is a non-essential but desirable addition to the still components. This will allow you to drink accumulated water without needing to break down the solar still, inevitably affecting its efficiency.


The best part of this life-saving device is that for something that collects water from seemingly nothing, the solar still is amazingly simple to build. Here's how:

1. Dig a pit approximately 4 feet wide and 3 feet deep. Use a shovel, hand trowel, a digging stick or even your hands in soft soil or sand. Look for a sandy wash or a depression where rainwater might collect.

2. . In the center of the pit, dig another small hole deep enough for the water container.

3. Place the container inside, then run the tubing from the container to the outside of the pit. If there is tape available, tape the tubing to the inside of the container.

4. Blanket the pit with the plastic sheet, evenly on all sides, but not touching the bottom of the pit. Anchor the corners with rocks.

5. Find a small rounded rock to place in the center of the sheet, over the water container. This will keep the plastic centered and control any flapping from the wind. Gently push down on the center weight until the sides slope to a 45º angle. If the pit is dug deep enough, this should leave the center weight just a few inches above the water container.

6. Next, secure the edges of the plastic sheet with rocks and dirt. Make sure there are no places where moisture can escape.

7. Close the tubing end with a knot, or double it and tie it closed.

Within 2 hours, the air inside the still will become saturated with moisture and begin to condense onto the underside of the plastic sheeting. Because of the angle of the plastic, water will run down towards the center. Finally, drops will gather and fall from the apex down into the water container. As the container fills, simply sip fresh, sterile water from the plastic tubing. In especially dry conditions, water output can be increased by placing succulent plant material inside the still.

The Solar Still only takes about an hour to build. If constructed correctly, it can yield about a quart of water a day. And although the palm trees may be noticeably absent, you will have made your very own oasis in the desert, quicker than Hollywood could.

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