How much water is there on the Earth?

Can someone make a comment on the sustainability of our current water consumption, in terms of the US, other parts of the world, and the world itself?<p>If we are not living sustainably, should we expect more investment across the world on things like desalination plants (I understand that desalination is really energy-expensive currently, but will that change by much?)

Every time I see this it amazes me how little rivers represent of the whole fresh water available and how much Antarctica does.