If you did elementary Chemistry, Science or Physics...or indeed if you have boiled water for pasta...then the science of desalination is probably familiar to you.
Salty water is boiled. When it boils, the steam is actually free of salt, so if you can collect the steam and then reconstitute it to water (by cooling it back down) that water is salt free...and indeed there is a salt residue. Often in the science lab that is what you do to collect a soluble slat.
On the face of it the science is attractive in our present water crisis, if it were not for one small thing. And that is the big orange block at the bottom of the schematic diagram marked HEAT
Heat of course is costly to produce, and there has to be a weighing up of the relative benefits. (a relatively good discussion of issues involved here)..
The major way to defeat the cost issue is to build big rather than small, of course the trouble is that in election times where each side is calling the other chicken there is a tendency to tokenism, in order to be seen to be doing something.
Tokenism usually means the making of a gesture which looks like the real thing, but in reality is designed to give the impression of activity rather than actually embracing the difficulty. ( a related but different issues about the relative cost of 'organic produce' is here . The question becomes at what point does the activity actually become a reality or are we content that it might be some sort of chimera.(some sort of fanciful mental illusion or fabrication.) .... maybe more coming