Question: when you say water, what about it?

Water Challenge answered on 19 Jun 2014:

Hi Arianna,
When I say “water”, I mean water in nearly all its uses. Like for growing crops; like for hydro-power purposes; like for cooling nuclear power stations; like for all domestic uses (drinking, cooking, cleaning, washing and so on). Even beer making requires quite a lot of water, as do many industries like steel making. The only limit of my definition of water is that it must be “fresh” water. This is because salty water tends to be corrosive and can’t be used for agriculture. Showering in salty water leaves one itchy because of the salt crystals. There are very few human activities involving water where salt is not a problem. Fishing and sailing at sea come to mind, for instance, as the main activities where salt can be tolerated.
The problem is that while the sea has seemingly endless amounts of water in it, the same cannot be said for fresh water. It is a very limited resource and we would very much like to find ways in which we can increase the amount of fresh water.
What I am looking for is people who have interesting ideas about how we can make this happen, sustainably and at a reasonable cost. Do you have any ideas ?