Sometimes a flexible hose goes here. This is easy to work with, because in that case only a threaded T-piece has to be attached to the cistern or to the stop tap at the wall inlet.
As in the diagram below.

Usually a standing toilet is equipped with a (12MM) pipe. There is usually too little space/clearance on this to place a T-piece in between. In that case, mount a compression fitting on the pipe. There should then be a
piece of approximately 1.5 cm must be sawn out of the pipe to make room for the compression T-piece.

A: Compression piece 12mm F1/2" 12mm

B: Built-in stop valve

See image below.

If you have an existing built-in toilet, it is still possible to make a connection to the water reservoir behind the wall. We are
specialized in this and can do this for you without breaking work.
The end result is a (design) stop tap on the back wall without visible pipes, to which the shower hose can be connected. One
situation as shown in the picture below.