The bathroom floor in my flat that I rented out to a very reliable person developed stains over a short period that she was away. I have inspected beneath the bath (after removing the side panel) and there is no leak. There is also no leak from the ceiling or from the flat above. The radiator is not leaking and the flat below has no leaks on their ceiling. She doen't use water to clean the floor.
I would be grateful for any ideas about the course. A photo is below.
Thanks
Dave
