The solar still was cooked up by two Department of Agriculture Scientists. So far, I've found clear, opaque and black listed in various references on constructing one! You must also factor in the 'sweat equity' in constructing one of these things. 'Dig a hole approx. 4' square by 3' deep' is the MINIMUM size I found.As an exercise dig one sometime. Don't drink any water either.Remember, this is a survival situation.If you succeed remember that a series of holes must be dug after the immediate water has been distilled from the first hole.Now try the plastic bag wrapped around living vegetation. As John Wiseman points out in his SAS book, The water may be 50' down. The tree is a natural waterpump.<br><br>