Just to make sure I understand the principle, transpiration bags get the water that is a byproduct of sugar production during photosynthesis.

So that's why the bag has to transmit light. The bag also has to be airtight and weighted down so that water will condense out (rather than venting as vapor) and collect at the bottom of the bag. The branch you pick should also have plenty of leaves and get plenty of sunlight.

Is all this correct? What do you recommend as a good bag type? Grocery store vegetable bags? They're very thin and transparent, but appear to be water-tight.

Is this deciduous only, or will evergreens work in winter?

I haven't tried it yet, but I know a bit about plants. All plants transpire somewhat, as part of the pumping mechanism. Deciduous plants will do it the most, followed by coniferous, and various desert plants such as cactii will do it the least. Which is too bad, because the desert is where you need it the most!

Watching people ride bicycles and riding one the first time are two different things. I would no sooner hand a child a book by Lance Armstrong than trust ANYTHING in a survival book without trying it myself. Options and redundancy are valid only if the methods are. I tried the solar still. I tried drinking seawater. I did these, and other options under guidance in survival schools. My military instructor said the manual page on solar stills was excellent- as tinder. I persisted with 3 more personal attempts in civilian life. I finally found a fantastic option in lieu of that plastic sheeting. It's called a canteen. <img src="/images/graemlins/grin.gif" alt="" />

Would using seawater as the condensing fluid work better in a coastl situation? Maybe if you found yourself tropical island stranded a la Tom Cruise <img src="/images/graemlins/wink.gif" alt="" />

Flip

Tom Hanks <img src="/images/graemlins/wink.gif" alt="" />

I always thought it sucked that he lost the survival thing when he hit the water. That would have made the movie more interesting for me, seeing him use all the gadgets <img src="/images/graemlins/grin.gif" alt="" />

Please believe me that I laughed heartilly after I realised when I read Alkaloids and thought Altoids that it confused me why people would think minty water would be bad...

Rena

Lysdexics Untie!

Doug I actually do not recommend the solar sill either. What the intent of the article is to set the record straight because there are errors on both sides. No it is not a great thing to precure water in the desert but it is not completely useless either.

Where I think its best use is as a still to decontaminate bad water. While boiling and chemical means can deal with bio hazards. They do nothing for other water contamination sources such as alkaloids often found in desert water sources or salt from sea water. And as I said it is just another option.

I do not know if it is still available but years ago I ran in to a product called if I remember right was tedlar. This was 1 mil thick and textured on one side. It was a very strong plastic that looked a lot like saran wrap. The texturing helped the water to collect better and run into the container. Being so thin Carrying a one or more large pieces was easy.

Actually I've read that most SAR teams prefer you lug an 8x8 piece of plastic. That size is more convenient to wrap your dehydrated corpse in.
Ed