A lot of the desalination projects in the Middle East are intended to provide large volumes to cities.
I think a lot of them are reverse osmosis units, but I am not sure about that at all.

Here is something about a distillation plant in Saudi Arabia
http://www.water-technology.net/projects/shuaiba/

They tell in the article why they used flash distillation instead of reverse osmosis, but they note in passing that reverse osmosis is a common method too.

This article outlines a bit of the scale of the problem and the problem of meeting it with solar desalinization plants.
http://www.theoildrum.com/node/3520


Edited by scafool (01/30/09 11:09 PM)
_________________________
May set off to explore without any sense of direction or how to return.