Hi all. Just moved into a friends house, and the upstairs shower is leaking, badly! From the top, there is a PVC white drain, that goes down into a deep U bend, that then leads off down the walls somewhere. We have removed the drywall (ceiling) from directly below the shower to gain access. All we can see is the bottom of the drain, and the ubend followed by the pipe disappearing into the walls. The shower floor itself appears to have been recently re-done. Not that I am an expert in any way, but it looks pretty new. The floor is a mosaic of fairly small non-skid tiles, approx 2" across. There does not appear to be anything other than cement or dark grey grout inbetween the tiles, and at the wall/floor joins. Is there some kind of sealant we can apply to the grout? It does not appear to be cracked anywhere. I have made sure that the tap fitting itself is not leaking by pouring water from a bucket directly onto the floor of the shower. (It rained downstairs from around the PVC drain). Do we rip it all up? Or is there an easier fix? I thought there was supposed to be some kind of catch tray under the shower floor? Am I wrong?