This is quite a common fault. The symptoms are that the wall and surrounding area is full of damp and the paint is bubbling. If it’s coming from the floor then a small pool of water may form on the floor when someone has finished showering. There are quite a few things that could lead to a leak on the shower;
The shower waste. This is the hole in the shower that takes the waste water to the drain. As you can see, shower traps are either plastic or brass. At times the plastic ones could crack and leak into the shower floor. If it is the trap, then we will have to chisel up the shower floor and replace the shower trap.
The 50mm PVC waste pipe from the shower trap to the outside drain may be leaking. The leak will probably be on a joint and will also probably be because the glue used to join the pipes was not of good quality. We will again have to chisel up the 50mm PVC pipe and replace it.
Tile grouting not done well around the tiles. This is probably the most common and yet most overlooked fault. The shower floor needs to be inspected and checked for any obvious cracks and breaks, especially around the actual shower trap exit. The other place it could leak would be around the actual taps/mixer of the shower, where the grouting is also at risk of not having been done properly. We will have to take out the old grouting/ cracked tiles and re-do.
Water pipes in the wall of the shower are leaking. The water pipes leaking will result in a constant leak of water and not just when someone has showered. We will have to chisel up the tiles and repair the pipe.