I live in a terraced house that at some point had a back extension, so the original back of the house is now inside this room.so waste pipes from the bathroom run down this back wall, the sewage one is ok, goes straight into the ground and is completely covered as it should be but the bath and sink waste pipes run down into an open drain with a grate on top, this has been covered by a built in seating area so is not visible but does get smelly and mouldy. Is there anything we can do to solve the problem? Like somehow concreting over it or moving it?
