Its a simple concept: you dig a shallow hole, lay in a clear sheet of plastic and wait for the sun to do the work. But has anyone successfully built one and collected water?

TRO

Yep. They work. I used to make them in Arizona. Even there, when it is hot and sunny, the amount of water they collect isn't that great. And it takes a while. I would use another option if I had a choice.

Tanspiration bags on vegetation will produce meaningfull amounts of water, assuming you don't tie them to posion oak like a local 'survival instructor' I quietly watched during a local community sponsored class. True solar stills cost far more in 'sweat equity' than gain.

Yes, I've used them before, and as with the transpiration bags, it works a lot better if you add vegetation to the hole first. Busted open cactus makes pretty good solar still moisture source.

I have used them and like everyone else has said unless you add some plant material (or urine ) you won't get much production. Transpiration bags are better, but in either case if this is your only source of water make more than one still.
I usually carry enough plastic to make at least 4.

Oh, they work. Just not very well. If you are near the ocean, I'd use them by digging down below the high tide mark, but that's about it. They are better rain catchers.

Built, yes. Collected water, not much. Even in the 100 degrees of central CA in August. With some greens in the hole to boot.

I was always amazed at my USAF survival manual that showed one with a flight helmet in the bottom to collect the water. Besides requiring a deeper hole, who wants a little bit of water that tastes like sweat???

What bags do you use to collect transpiration vapor? I want to add some to my gear but I'd like input on the type, size, brand if possible...

Thanks.
-Blast

I use clear trash bags the size for an office can. I don't have a particular brand I like as long as it dosen't have any holes.

I think that the solar still deserves a good scientific test. So, this summer/spring, I believe I'll be digging a few holes in the backyard ('s OK, some idiot did a 720 degree turn back there in the last ice storm and killed off half the grass).

Parameters:

1) Air and ground temperature
2) Time to dig
3) Soil composition (read: clay)
4) Additives (vegetation)
5) Water collected (over time)
6) Plastic used
7) Amount of daylight

Am I missing anything? I'd like this to be definitive.

Oh, and humidity in and outside the hole.

Sheesh, I'm going to have to buy a datalogger--I wonder what else the wife is going to use against me in a divorce?

In the book "Adrift" by Steven Callahan the author's solar stills got him through times of otherwise no water. He was in perfect conditions, though: very moist source (seawater) in very hot & sunny weather. IIRC he netted about 2 pints/day from each still. His stills were small and purpose-made for use at sea although they fell apart after a while.

When I read the book, I remembered all the nay-saying about solar stills & the sweat equity they demand. While they certainly won't produce bountiful springs of water, I think they should be among your options IF:

1 - you do the work to set them up at night, not out in the broiling sun

2 - you utilize a moisture source other than the ground itself: cut up vegetation, seawater, etc.

3 - take advantage of natural depressions (or available containers) rather than digging big holes from scratch

I think solar stills are best considered adjunct water sources that are nice if they work out, but are not to be depended upon as a primary source. I wouldn't throw out the entire concept, though, as seems to be common. I think Callahan's real-world experience with the stills is not to be dismissed lightly.

Just a small point, but Steven Callahan used inflatable solar stills rather than one that is dug into the ground. They required constant attention and eventually began to fail, be he wouldn't have survived without them. Great book, by the way, talk about a guy who just wouldn't give up!

Hmmmm... I have an idea! If I was traveling by vehicle through the desert, it might be a good idea to carry an inflatable wading pool. Inverted, it would make an instant above-ground solar still.

Note to self: Tomorrow, incorporate desert survival equipment company and start selling kiddie pools as solar stills at a 500% markup.

Home depot sells clear 55 gallon trash bags that would make excellent transpiration bags AND are large enough to fit over most branches and also be used as shelter.

Besides, you could also put it over your head, tie it off at the waist, and have an excellent see-through rain shelter ... for a few minutes anyway.

Ken K.

8)How wet/damp/dry was the soil?
9)What time of year, and when was last measurable rainfall?
10)How much water or other liquids did you tank up on before or during the construction?
11)Keep track of #10 and compare that to what you gained from the still.

The last time I read about one of these things, I think they recommended a hole about three feet deep and almost as wide. The last time I had a hole that deep dug in my yard here in WA, it was a grave for my 50# dog. I hired three 15-yr-old boys to dig it on an April day that was about 50 degrees, in shade. They took turns loosening the soil with a 5-ft steel breaker bar, scooping with a pointy type of shovel, and removing many large rocks by hand. It took them two solid hours, they worked pretty steadily and they were sweating like pigs.

I dug a hole in my open field that was two feet deep and one foot across in the summer, and the soil was almost totally dry all the way to the bottom. And if I had added all of the above-mentioned ingredients to the hole to increase the possibility of producing water, how much would the dry soil have absorbed in the process?

I just can't see that kind of effort being worth the amount of water that most solar stills would produce.

Sue

Good points. My purpose in the grand "experiment" is to find out what factors contribute to water production and what factors detract.

If a solar still, once dug, continues to produce a half pint of water daily with no intervention...it may be worth it. If you have no means of purification and can transpose dirty water into clean with it, it may be worth it. I just want to find out, rather than relying on (not necessarily useless) the consenting majority.

In a true desert, I would be.

On a coast line or in a moist grassland or woodland, I could see it. But in the later two, you can usually find a surface water source easier than you can dig the pit.

Generic parameters from this experiment: the water table is 250 below ground on average; soil is clay. Summers are hot and humid.

What I expect to find is some type of curve where temperature, humidity, etc correlate to an increase/decrease of water production.


Call me overly curious, but I'd just like to know what a solar still is capable of and what to expect from one if I build it