I managed to get an endoscope down one of the 32mm basin drains by removing the basin trap. First the drain pipe is pretty disgusting with black sludge from, I assume, soap etc. I live in a hard water area so I don’t know if that makes it worse. So, going down the drain it’s difficult to see which way the pipe goes as I can’t tell what the orientation of the camera is. The endoscope is not an expensive one and has a short focal length so not a lot in focus at the same time. Anyway, going down below the floor in hits pooled water, which I assume is caused by a sag in the pipe work, or possibly a partial blockage further on. What can be used down the vertical basin drain pipe to rod the pipe work to the stack? A snake?
There are no rodding points on the 2 en-suite drainage pipes. The only entry points are the basin drains after removing the traps. The only way I can see to fix this pipe sag (or belly), if that is the problem, without lifting the tiled floor or removing a section of ceiling below is to install new surface drain pipes in the en-suites and drop the pipe into the 110 mm pipe through the floor at one point. Maybe a 50mm pipe with the 2 showers and 2 basins teed into it.?
Any other ideas would be welcome