I've got an engineering question posted on my site regarding a portable desalination device (potentially using reverse osmosis), if anyone has ideas: http://zombal.com/zomb/scientific-design/emergency-desalinat...

Like one of these? http://www.campingsurvival.com/kahaemdewama.html

Evaporation also becomes a lot cheaper when you get most of the energy from the waste heat of a power plant.