One of the pitfalls of installing a wall-mounted toilet is that the tank is behind the wall, so it needs to be installed when the bathroom is being built, otherwise, you’ll need to do some renovations to get the tank in the wall and the toilet mounted properly. Depending on the depth of the wall, you may also need to widen it to fit the tank properly, which could result in less space after the wall is replaced. Issues with the tank will also require you to remove the wall to repair or replace it.