Rednadnerb wrote on 17/02/2017 :
My neighbour has a pool of water that mysteriously appears on her bathroom
floor at random times usually once or twice a week.
It appears on the floor in the 18" space between the toilet and the bath and
appears even when she is not in the flat.
I strongly suspect that it is coming over the top of the pan as I have found
the lip to be wet (she is in a 1st floor flat so is this even likely?)
It has been going on for ages, I have brilliantly suggested a time lapse
camera but she won't have that in her bathroom. I have also suggested putting
one of those blue things in the cistern.
Any other ideas as to how to get to the bottom of the mystery pool of water?

Any possibility this might be appearing from below, as in a tiled floor
on concrete, with the water coming up through the tiles?