Yes it is possible.
You have two choices (possibly).
A simple method may be to just join a pipe to the existing water supply and run this down the wall and into the new close coupled cistern. This may look a bit untidy but if it's painted the same as the wall you will not notice it much and never notice it when using the toilet...
A neater solution - depending on the circumstances - may be to route the new water supply from under a suspended wooden floor straight up into the new cistern. Obviously not practical with a concrete or tiled floor.
Your plumber will be able to advise options, complexity and a ball-park cost. You will usually be charged for one and a hlaf or even two ball-parks when the job's finished.
Good luck...
Peccavi, October 2009
