Liquids should probably not compress

As described and displayed in this discussion, you can see that in a room full of water the tiles at the bottom of the room are denser than the tiles at the top. Presumably this is supposed to reflect the increased fluid pressure in the bottom tiles, but only gases behave this way to any significant degree, not solids or liquids. Here's the Wikipedia article on water that describes the compressibility of water. Basically, at 400 atmospheres of pressure water only compresses less than 2%.