Desalination has been around for quite some time, but the alternatives are so much less expensive that it's adoption won't increase until populations reach critical levels.
> The Perth plant, which uses technology from Energy Recovery, a firm based in California, consumes only 3.7kWh to produce one cubic metre of drinking water.<p>This comes out to $0.37/264gal of water, assuming $0.10/kWh.<p><i>edit</i>: should have read the next paragraph before posting :-/