My brother just gave me instructions via Gmail chat on how to create a solar still to make clean water while on water restriction in Nashville.
Jason: if I remember correctly
you dig a hole
cover with plastic
put a vessel (empty) in the middle and put a small rock on top of the plastic and center over the vessel to catch the water that condenses on the plastic film
I suppose you could put river water in the hole to up the moisture content in the still and thus produce more water