Plumbing a basin waste pipe - why is it so difficult?
Plumbing a basin waste pipe - why is it so difficult?
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TUS373

Original Poster:

5,216 posts

311 months

My blood pressure is going through the roof. I have a downstairs cloak room now full of an assortment of plumbing bits, bit this is not coming together. Turning to the PH brotherhood to alleviate the tightness that is in my chest!

We have a basin where the underside is visible. It has a chrome bottle trap, looks nice, but when it was installed 10 years ago, it would not stop leaking. I have deduced that the the wall was drilled through (outside wall, cavity, inside wall) but that trajectory goes off at a slight angle. When the sink waste was connected, there is a sideways strain that caused leaks.

I have some recollection of when the sink was fitted, but had one guy plastering, another plumbing, another tiling. I do not know who drilled the hole or at what stage.

At time of installation, I recall buying 32mm chromed (metal) pipe, but that was too small for the chrome bottle trap. It actually took 35mm chromed pipe. The bottle trap came with 300mm of 35mm chrome pipe, but there was nothing to attach it to at the wall. I therefore found a long piece of 35mm chrome pipe, took it through the wall, then had push fit 34mm 90 degree bend, taking it to some pipe to the drain, that is also 35mm outside diameter. It kind of worked by trial and error. I had to resort to using Plumbers Mait around the sink waste to stop it leaking. Took ages to get it OK, but I saw from underneath how badly everything was misaligned. Even the bottle trap was at a slight angle.

I have just had to replace the click clack pop up waste so I have had it all in bits, and I can see that things are off course. Reassembly inevitably caused leakage again. I am trying to fix it properly now - bit it is really doing my nut. I buy 32mm fittings - but the outside diameters can be larger, and that causes me problems.

Rather than taking a long metal pipe through the wall all the way to bottle trip, I deduced that plastic through the wall is better. It can bend a little. Then if can attach a length of chromed metal pipe from the sink to the wall,I can get everything straightened up.

Problem 1 - attaching 35mm metal pipe to plastic pipe
I want to join different types of pipe, hide the join, and just leave the nice chromed section of pipe in view. I found a nice little converter that is chromed, fits 35mm pipe on one side with a compression fitting, and can take '32mm' ABS pipe to the other side, solvent fixed. If I can wide the hole in the tile, I may be able to push this sufficiently into the wall that only the chrome part is in view, plus I can use a chromed cover. However....

Problem 2 - 32mm ABS pipe is even fatter than 35mm pipe
So - I tried to shove the 32mm ABS pipe through the wall, but it just won't go in. The pipe is fatter still than the rigid 35mm pipe that there was there before. This means - to use a solvent connection/pipe, I would have to wide then hole - all the way through the wall. That is turning one job into a bigger, messier, more destructive one. I also risk damaging the tile. I was thinking I could use the other bit of 32mm plastic pipe, that is narrower but...

Problem 3 - the other section of 32mm plastic pipe will not be suitable for solvent fixing
I am assuming that the lovely 32mm plastic pipe, that easily passes through the thickness of the wall and would allow straightening up of everything, is only for compression fittings. Is that right? So solvent 32mm pipe is thicker, with a larger outside diameter (making it 35mm), than 32mm compression pipe?

So, I am feeling rather stuck!

I expect that best practice is to use one fixing system end to end for standardisation - all push fit or all solvent.

  • 32mm Solvent pipe is too fat for the wall, but I can easily join it to the 35mm metal pipe to the bottle trap and hide the join.
  • 32mm fits through the wall, but it would be compression fittings. Even if I could hide the change, it will be tough joining 35mm metal pipe to 32mm plastic pipe.
I was wondering if I can bodge 32mm compression pipe into the solvent end of the fixing, with the other side being compression to the 35mm metal pipe. Maybe using Plumbers Mait, but I would think any twisting of the pipe when it is in situ is likely to cause it to leak. It would be a weak spot, and if it did leak, would drip water into the wall cavity.

Other than that - I have to re-drill the thickness of the wall. I think widening a hole with a circular SDS cutter will be difficult, but is there such a thing as a ~38mm solid drill bit? I guess not, it would be very heavy.

So...I am stuck. Please help if you can!

Thanks!



Black_S3

2,844 posts

218 months

fk me i think youve just summed up every plumbers day in one post. Prob pictures would help.

TUS373

Original Poster:

5,216 posts

311 months

Oh yes! I could not do with the frustration professionally!

I think what I could need does not exist. A 35mm compression end, chromed, to a 32mm push fit reducer.

I have a Mcapline converter, but like I said, it is for solvent pipe...and 32mm solvent pipe is too fat!

Black_S3

2,844 posts

218 months

TUS373 said:
I have a Mcapline converter, but like I said, it is for solvent pipe...and 32mm solvent pipe is too fat!
Think of this but with a light sand paper (wet paper is best imo) on plastic pipe https://www.youtube.com/watch?v=aZcd8wgUXPM

You'll run out of space by the sounds of things if you try using any adapters for push fit to solv weld etc.... its only a ballhair youll need to find before solv weld pipe will work but it does need to be smooth so no silly 100 grit paper that leaves scratches for the push fit rubber.



TUS373

Original Poster:

5,216 posts

311 months

Thanks. What I meant was....I have the 32mm solvent type pipe, and that fits the adapter. However, solvent pipe is thicker, so I cannot get it through the wall. I need a narrower pipe (pushfit) or wider tunnel (solvent pipe) through wall.

Black_S3

2,844 posts

218 months

you can get push fit waste pipe as well if that solves the problem... they're always listed as same size but there is a differnce with the push pipe being smaller

TUS373

Original Poster:

5,216 posts

311 months

That is right. Problem then though is how I connect the slim 32mm push pipe to 35mm metal. Everything seems incompatible!

Simpo Two

92,939 posts

295 months

My sink waste blocked up terminally a few days ago and no chemicals would shift it. So I took to the plunger... but instead of shifting the blockage, the water pressure undid the bodge I did in 2008 and it started dripping. Arse.

The plumbing under the sink always did look a bit like a map of the London Underground but there was nothing for it but to shift all 3,000 bottles of cleaning products out of the cupboard onto the kitchen floor, take the door off to get the shelf out, undo all the plastic waste sections, shovel out the crud with a long handled teaspoon and reassemble it. The waste piping always was rather a assortment of oddments and nothing fitted together perfectly, so I went down to the local merchants, asked for advice and came away with a tube of CT-1. The bodger's favourite they said.

I carefully reassembled all the sections with PTFE tape, which you're probably not supposed to use but I had some anyway, and put CT-1 onto the threads just to be sure, and left it for 2-3 hours. Then I tested it by putting a small amount of water down the sink. Bad idea. Not only did the original leak start again, but now there was a new one at the start of the U-bend. Arse. When the dripping stopped I took the tube of CT-1 and set about every joint, to teach them a lesson.

Soon afterwards, during the process of cooking supper, and momentarily forgetting that my kitchen waste was in no real state to receive water just yet, I drained the spaghetti into the sink. Arse. For some time I was on my hands and knees, mopping up the dripping water with a cloth and wringing it out over the sink. During this process I wondered how there could be so much water. After about 10 wringing-outs I realised my mistake and wrung the cloth out into a bucket instead. I then left the U-bend to drip until it was empty.

Three hours later, it was still dripping, albeit very slowly, and now it was almost bedtime. Again I set about the joints with even more CT-1, applying directly at the front and using a spatula and wet finger to smudge it round the back and hopefully not miss any bits. By now the base of the cupboard, the cloth, the spatula and my fingers had nearly as much CT-1 on as the joints. It's dreadful stuff; no amount of handwashing really shifts it.

Today I have left everything as it was, with 3,000 cleaning products all over the floor, but may test it again tomorrow...

TUS373

Original Poster:

5,216 posts

311 months

Brilliant. I can relate to that.

I have said Arse quite a lot over the last week. I may have to turn professional as a plumber in order to get the money back on all the traps, wastes, solvent, pipes, spanner, laser level etc. I started on this journey watching someone on YouTube claim to show how to fix a stuck click click waste. The blooming thing would not budge for me, so from repair to replacement....then everything has cascades from there. Next week, I will no doubt be learning how to reinstate a house wall after chewing through it with an SDS Titan drill. My mistake was believing that in the 21st Century that 32mm pipes all measure 32mm. I was wrong.