Quick answers
Is a concealed cistern worth it? And if it breaks, will the wall have to be broken?
It saves space and makes cleaning easy. Its mechanism is usually reached through the flush plate opening, without breaking anything. It can only go in while the wall is open.
A concealed cistern is fixed to a metal frame inside the wall or behind a low boxed-in section. The same frame holds the wall-hung toilet, which doesn't stand on the floor. Of all this, only the flush plate shows.
The first gain is space, because there is no cistern sticking out. In a narrow WC this matters: there, the frame was fixed against the bare brick before the plastering. The second is cleaning, because the floor under a wall-hung toilet stays clear. In another bathroom, a built-in shelf was formed around the frame.
The usual worry is what happens if it breaks. On most systems the flush plate comes off, and through its opening you can reach the float valve and the flush valve, which are the parts that wear. That is why the flush plate is never tiled over.
What can't be done is adding one later: the frame, the drain and the water supply go in while the wall is open. If you want one, say so before the strip-out. It also needs enough depth in the wall, or room for boxing in front of it, which is judged on site.
The plumbing is work for a plumber. Before the wall is closed, ask whether the connections will be checked for leaks.
Jobs that show it
Bathroom Renovation with a Walk-In Shower
A bathroom with dark old tiles and a tub was stripped out completely and became a bright room with a step-free shower, a wall-hung toilet and a new basin.
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A Narrow WC Rebuilt from the Brickwork Up
A narrow WC was stripped back to the brick. A concealed cistern and new supply pipes went in, the walls were plastered and the floor was laid with new tiles.
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Bathroom Renovation with Striped Tiles
An old bathroom with a bathtub was stripped back to the brick and rebuilt with new pipework, a plasterboard ceiling and striped tiles.
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