Kitchen sink waste pipe

7 Nov 2008
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Hamilton, Lanarkshire
United Kingdom
Sorry if this is obvious, but I have read the Wiki and the FAQ and can't find an answer.

The last trap (there are two after the pipe) at the end of my sink waste pipe has came away from the outlet at the wall. It looks like the trap doesn't quite reach the outlet far enough to fit tight against it.

In this situation is it best to use a sealant/putty or buy an extension trap and cap?

I've attached a pic for reference
Many thanks in advance,

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It is difficult to see what is the exact problem. In the picture is the issue with the lower joint, where it looks like the white compression elbow exits in to a black waste joint?
It could be they have worked loose and just require stripping down and refitting. I assume this problem has not always existed?
I think what you are saying is that the horizontal pipe is not long enough resulting in the compression elbow not sitting onto the waste:?:

If that's what you mean, then you need to replace the horizontal pipe with a slightly longer piece and possibly renew the compression elbow or at least the internal washers. Personally I wouldn't use any sealant.
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As above but I'd also fit the new longer horizontal pipe last after all the sections to the right of it.

First of all, thank you all for your kind help.

Yes, sorry the picture wasn't particularly revealing. The issue is at the lower joint where the compression elbow meets the black waste joint.

The black waste joint is actually starting to rust. Have any of you had any luck repairing a joint that is falling apart?

I bought some sealant, but also a tub of Plumbers Mate and some couplers/extensions too. Is it possible to add a extension to the elbow?

Again, many thanks.

The black waste joint is actually starting to rust. Have any of you had any luck repairing a joint that is falling apart?

to a point, yes;) but we need to see what the rusty pipe stub is - can you take the pipes apart and post a photo - perhaps using a bucket under sink while waste is out of use.
For a long term fix I think you'll need to remove that rusty pipe/joint and replace that but without seeing it better and what it leads to after the wall, it's hard to visualise what you might need to replace. As Nige mentions, a better idea of what's after the hole in the cupboard would be ideal.

What does the the rusty pipe/joint connect to, is it into a cast iron down pipe or similar?

Happy new year and many thanks again for your help. Please accept my apologies for the delay in responding. I found that the waste joint was covered in god knows what, rust, dirt, etc that had formed a solid mass, covering it and not allowing the connector to go on properly.

I also found that pipe is far too short, push one part in further and the other two parts fall off!

Stupidly, I bought a 40mm pipe for the 40mm connectors, but the connectors are too loose around them. What pipe size is needed here please? Should mention it is a push fit set up here.

Many thanks,

The connectors shown in your photo are compression and should fit both pushfit & solvent-weld pipework.

Which section are you having difficulty with?
Sorry, it's most likely the way I have explained it

The pipe that is currently being used for drainage is too short causing leaks.

I bought a new 40mm outside diameter pipe but it is too narrow in diameter for the circular things (the ones I have a 40mm) that you tighten around the pipe when attaching it to sort of 90 degree elbows.

I am getting myself mixed up with the pipe size. I can't take the current pipe out to check for its size as it needs to stay in place for very basic drainage (emptying cups etc).

What is the next pipe size up from 40mm please? Sorry for getting the names of stuff wrong also.

There are larger sizes above 40mm, but you do not have or need them. It will be 40mm.

The fittings must be unscrewed completely so the black rubber washer inside can be placed over the pipe first. If the pipe is loose, the washer has probably been pushed out of place inside the fitting.
40mm is what you have and is the correct size - next up is 50mm which is not what you need.

If you unscrew the fittings you have, you should have the backnut (white nut which you unscrewed), a black rubber ring and (usually) a flat plastic ring.

To make to fitting fit onto the pipe:

Unscrew the fitting
Put the white backnut onto the pipe with the threads facing the end where the fittind will go
Put the plastic ring onto the pipe
Put the black rubber ring onto the pipe with the narrow end towards the fitting
Put the fitting in place with the pipe approx 30/35mm into the fitting
Slide the backnut and the two rings towards the fitting
Tighten the backnut up until it is firm on the pipe

That's me finished the job ten minutes ago. Cut the new pipe down to size, arranged the backnuts and rings in order. A test found a slight leak at the outlet end, but tightened it up more and so far, so good.

The real test will be the dishwasher and washing machine.

Can't thank you all enough for your guidance. I really do appreciate it.



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