You are correct in theory and application. I have yet to see any still produce enough water under the best conditions to justify the physical effort. I can't see digging a 4'X4'X3' hole if my water supply was non existent or critically low. I see little need for a solar still in high altitude snow pack or tropical forest. Solar stills imply HOT, arid or semi arid complexes. Vegetation is usually of reduced leafy material, with subsurface root storage systems containing most of the water. Plastic sheeting is not without use: An expedient shelter, to catch rainwater and fabricate a ground signal. For that use a colored material would be prefered. My strategy is to carry water at all times, a lesson I learned the hard way. I keep plenty of charts, and do my best to augment them with information from locals about traditional catchment basins, small wetlands and seasonal streams. The best of our topos are a finite abstraction and dated.Knowing the water finding stategies of the fauna is invaluable. With a secure water supply on hand an individual is much better 'equipped' to rationaly secure additional supplies.<br><br>