volumes are functional only
You need more than just a volume to make water. Volumes only handle the physics. FluidSurfaceInfo is a good way to make water look good. Just be sure you make a decent texture for it. And be *sure* to playtest it... There are a lot of polys in even a single FluidSurfaceInfo, and they *do* take a chunk out of your framerate if you're not careful. More than one at a time can be a slideshow.
And if you're a fairly n00b-ish mapper like me, don't bother wasting your time looking for a water texture in the included textures. There are only about 3, and they're highly customized for the maps they're in. I hacked one up, and trust me, it's not worth it. It will still look like n00b crap, no matter what you do.
For my n00b crap example, try out CTF-Z1Eagle1-2003. It has several examples of water done poorly.