Have you checked for plumbing leaks? If you have that much water on the floor, you probably have a tenent that won't close the door when having a shower. Stopping all water is not easy, the transition from floor to wall if grouted can crack and should be sealed, the toilet is sealed to keep its water in the pipe, but floor water can find it's way around the outside of the pipe. The vanity is also a problem, where water can run under it. Once you have made a swimming pool out of the bathroom, where will the water go.