My downstairs neighbours have complained of water leaking. after lifting my floorboards I can see that a plastic waste pipe has somhow come away at a compression fitting. I would like to extend the pipe so that it fits into the coupling properly as it seems a bit short at the moment. The problem is that I can't find any pipe of the same diameter. I think the diameter must be about 60 mm (will have to measure tomorrow) but it is definatly bigger than 40mm. This pipe was probably put down in the 80s or 90s. Have standards changes since then?