When squeezed to pressures and temperatures like those inside giant planets, water molecules are less squeezable than anticipated,'Less Squeezable', dang. I hate it when these guys get all technical.
Anywho, this is an odd coincidence as last night (Tuesday) on 'Universe' (H2 Channel) they had a program on 'water' and our Solar System. Specifically about Saturn's Moon Titan which is the only other body we know of with 'flowing liquid'. But on Titan it isn't water.
Titan is 'almost' like Earth in that respect and also that's it atmosphere is mostly Nitrogen and it has water (H2O. But on Titan the pressure is HUGH (don't know about any gigapascals) and due to the atmospheric pressure the 'water' is like Granite on Earth, it's that hard and compressed. And also because of that pressure the flowing liquid and lakes are Liquid Methane, and so is the 'rain'. And like Methane is on Earth, Oxygen is on Titan -- flammable. But on Titan Methane isn't flammable and we know on Earth it is.
The basic conclusion 'they' (numerous physicists who play segment hosts) all came to is that liquid water is really an unnatural state. It should be Solid like on Titan or a Gas like with Steam here. So finding any 'water earths' in the Universe is not likely as all the conditions are too exacting (and then I nodded off to my redcurrant nightmare of being butt-naked and in HS)
(just kidding, I'm really in a Firefight and have a gun (sometimes a pistol, sometimes a rifle) that won't fire at the 'bad guys').
[Hmm??? Maybe I did die in Vietnam after all?]