For the still to work you don't need to attain a rapid boil. A rapid boil presents it's own problems (melting your straw, soot on your condenser etc.) depending upon how much foil you have wrapped around your PSK you could form a smallish parabolic solar reflector box to heat the source water. Stretch clear plastic "garbage" bag over the top to trap heat and provide condensing surface and drain the condensate off from the bottom. This is a low pressure "augmented" solar still approach. Depends upon good sun and abundant water and a lot of foil.

None of these options has the potential for great amounts of production without much larger apparatus than we are likely to construct from the materials in a PSK. The solar approaches have the advantage that they don't require as much tending. you don't need to keep the fire going or prevent it from damaging the equipment. The disadvantage is that you don't work as fast.


A simple variant of this can be made by digging two troughs - one wide and the other narrow running east-west. Place a clear plastic bag length wise accross both trenches such that the southern edge of the bag just covers the southern trench. Use expedient props to hold up the northern edge of the bag so that it forms a triangle facing south with the open end either east or west. Fill the wider - northern trench with source water inside the bag seal the open end. As the sun shines into the bag it will warm the water and the entire interior of the bag. Some of the water will be evaporated and condense on the top of the bag where it will flow downhill into the southern trench. If you remove water from the southern trench and fil the northern trench you will get water. This is essentially the way some commercial solar desalination plants work