You would not be able to drink virtual water. It wouldn't make sense.
For example, if you drank some water in a Star Trek Holodeck, the water inside your body will instantly dematerialize once you leave the room.
As for SkyNet from The Terminator, it appeared to be an Artificial Intelligence that used computers all over the world to operate, much like Folding@Home does. Hmmmm......
Think what graphics will be like 30 years from-now. Then thirty years from THEN. Do you think it is possible for virtual realities to be better than the real world?
No need to think so far ahead. Just wait for five years and you will be amazed.