Plumbing mystery

Our house has been built with separate WC and bathroom, they are adjacent to one another. The waste from the bath and washbasin run underneath the floor. The WC waste is above floor level and is boxed in. The connections to the main vertical soil pipe are boxed in the far wall of the WC. There is a slight leak running down the vertical soil pipe. I assumed that if I drilled a hole in the ceiling below, I would be able to see the bath/basin waste pipe. The pipes run within 6" of the outer wall so I drilled where the X marks are. There is no sign of the pipe. Surely, it doesn't rise up as it passes the lavatory?

Can you borrow an inspection camera from the museum?

Have you opened up the panelling?

The bath & basin waste might be Tee'd into the soil-pipe, though no, it should not drop below floor-level then rise up - but recalling what I found in my first own home, there's no telling what some previous owner may have done.

The joint might be squeezed into the ceiling space but not visible from the inspection hole you cut.

I would carefully open the panelling to give you much better access.

I looked using an 8mm USB snake and my laptop through some 1/2" holes I have drilled. There is about 8" between the upstairs floorboards and the ceiling downstairs. Fortunately, the leak is from the bath/basin, not the lavatory.

Check the ceiling is level, the leak could be at the bath waste and the water will run on the ceiling between joists to the first point of escape which is the downpipe to ceiling joint.

Emgee

If the bath has a "shallow waste" then pipe for that and the basin could just have enough drop to run above floor level and be bossed into the stack. Will the bath panel come off?

As Emgee suggests ,it could be a leaking waste. Behind the panel cut out a section of floor between joists and use a mirror and torch to trace the pipe and check for runs on the plaster board.

Frank

I had to measure the distance between the ground floor ceiling and the underside of the floorboards hoping there was a section of boarding, but it measured 8", confirmed by direct measuring from the stairwell. Those pipes must rise up when they pass through the lavatory. Next week I will be in a position to remove the toilet which will give me plenty of room to work. I already know where the waste pipes run in the bathroom, a few years ago, I refitted it with all new stuff and also the toilet. Removing the bath panel confirms that the floorboards run at right angles from the wall and the waste pipes run parallel to the wall just below floor level. There is no sign of wet anywhere except lower down on the line of the vertical 4", 110mm main waste.

Edited By old mart on 15/04/2021 17:27:45

If the pipe rises up like that the lower run would not empty and you would have found the old piping full of water when you changed it.

Don’t forget to have a wet vac on standby when you do the job!!!

Good thought, Jim, I had forgotten my old Aquavac in the garage, it will make emptying the last water in the cistern and toilet bowl easy.

Dave, I just pulled the bath panel off to check, and my new connection is to a bend that is about 1" above floor level, so I might not have noticed at the time.

Was your house built in days when it was a sink and an enamelled cast iron bath stood on feet?

No, the whole estate was built in the early 70's when a lot of gerry building was going on. It didn't even have an electricity consumer unit, I retrofitted one myself. Even the central heating is only 15mm in a large semi.

I thought I would show you where the pipe actually was. Firstly, my cheap USB endoscope gave up the ghost and I was forced to go to Screwfix and get their cheapest self contained one. It is a Magnusson with a 1 metre flexible camera. It is much better than the broken one, not exactly cheap at £70, but easier to use and the picture is better.

I found the pipe below the floorboards, but hidden behind two joists. I cut a notch in the joist which ran parallel to the 40mm pipe and cut the pipe with the ratchet cutters, they don't leave a burr inside the pipe. The pipe was not properly inserted (about 12mm) and the rubber sealing bush was perished, no wonder it leaked. The strapped and glued adaptor has a smaller diameter boss than a modern one, so I had to make a one off coupling. I cut one end off a push fit coupling and removed the raised lettering on the od. I bought a 40mm tee with the screw up ends and the plastic rings just fitted the coupling and I could fit one of the rubber seals. The seal was too tight to push into the boss, so I had to reduce the seal od by 1mm using a scalpel blade. Wilr plenty of silicone grease on everything, I just managed to push it home. A new length of pipe 35mm longer than the original was fitted to just reach the inner wall of the 110mm pipe. As the ends of the old and new pipe were touching, I cut the centre stop out of a pushfit coupling and made a sliding joint.