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.