The best use for the solar still is as the end game in your water collection strategy. If you have already searched for water by going downhill, looking for seeps, etc and you haven't had any luck then you will have to find a place where surface water is reachable by digging. Find a low moist spot and dig. If you have dug through moist soil and have a fair sized pit already and water dosen't pool in the bottom, then and only then would a solar still make sense.
You should go out and build one, a big one, on a camping trip sometime. Make sure you have a wide mouth receptacle in the bottom and steep sides to the plastic so the water runs. Record the amount of water you drink making the thing and the quantity of water produced. They are a huge disappointment.
Transpiration bags work if they are large and clear. The bigger the better. Check limbs for bugs and bird droppings. The bags have to be sealed tight and left for a long time. You will still need to treat the water in most cases. If you use enough bags on enough of the right kind of trees you can produce water. In my experience this will produce as much if not more than a solar still with only a fraction of the work. Mac
