I have a Caroma (Australia) eco-style toilet. There is a recurring leak around the base but ONLY when the water supply main valve is turned on.
The toilet can have water in the bowl, and water in the tank, with no leak. There is no sweating on tanks, and no leaks from any of the visible attachment points from water main, or tank-to-bowl.
I have replaced the wax seal with no change to the leak issue.
With water valve on, it takes about 2-3 minutes before I can see water collecting round the base. When I fill the tank up, and turn off the main, the tank will drain itself, I assume into the bowl, as it does not appear round the base.
The water is clear and not stinkified so don't think it has anything to do with the outgoing pipe and seal.
Any suggestions as to where/why/how this is happening and a fix?