Plumbing advice please

Paperpumpkin

Hello, I’ve a small drip/leak under my sink and have located exactly where it’s leaking. It’s after the u bend, at the final join before the pipe leads out. The thread is good and tight on to the u bend itself, but the ring isn’t actually attached to the straight final pipe. Sorry, I don’t know the words to explain the detail! So how do I join the ring to that final outflow pipe? Should there be a rubber seal there?

I can’t upload a photo, but hope my description is clear enough.

Thanks for any help!

Le_Kirk

Have a look at this picture and you will see the seal (washer) that might be missing.

sevenhills

Paperpumpkin wrote: »

Sorry, I don’t know the words to explain the detail! So how do I join the ring to that final outflow pipe? Should there be a rubber seal there?

Thanks for any help!

https://www.ebay.co.uk/itm/Kitchen-Sink-U-Bend-P-Trap-Waste-76mm-Seal-1-1-2-1-5INCH-40mm-43mm-Outlet-/281382978609

Is this the one?

Looks like the seal may come with the pipe.

Ganga

Sound like you will have to loosen the plastic nut and make sure the seal washer and ring are on the pipe,re-fit and tighten up the plastic nut,job done.

Jackmydad

Make sure the taper on the ring is towards the fitting. The flat plastic washer goes the other side, nearest the gland nut.

Ebe_Scrooge

Ganga wrote: »

Sound like you will have to loosen the plastic nut and make sure the seal washer and ring are on the pipe,re-fit and tighten up the plastic nut,job done.

OP, I was going to say pretty much the same thing as this. Just a couple of points to add :


Firstly, once you've removed the joint - and assuming the rubber washer is in place and undamaged - take some time to clean everything really thoroughly. No need for any harsh chemicals, just a really good clean in warm soapy water. Ideally remove the fitting completely and give it a good clean in the sink ( not the sink that you've just removed it from !!!! ). In my experience, a little bit of dirt or grit either on the thread or the washer can prevent you from getting a good seal. An old toothbrush is ideal for cleaning the threads. Also clean the pipe itself, as well as the fitting.


Secondly, when you're re-assembling it, there's no need to over-tighten it. Too much pressure can distort the rubber washer - it only needs to be hand-tight. And be careful that the joints are "square", if that makes sense, and not crooked or cross-threaded. It's not at all difficult to remove and refit - sometimes a bit of a fiddle due to limited access. But since everything only needs to be hand-tight, you shouldn't need to faff around trying to get pliers and wrenches and what-not in there.


If the washer is missing or damaged you should be able to buy a replacement for pennies. If the worst comes to the worst, a whole new fitting will only be a few quid.

Paperpumpkin

Thank so so much everyone for your really helpful and patient replies. I’ve had another look and compared it with the ubend under another sink - and yes, it’s seems to be a black washer that’s missing. There is a blue one, but the other sink has a blue and a black one. I was puzzled as the u bend doesn’t seem to be attached to the back outlet pipe - no thread etc, but maybe just the washer holds it tight? I’ll try just ordering the washer - is there a specific size for the washer for a bathroom sink (like the photo sevenhills sent)? ....And what’s it called?! I’ve put “u bend washer” into amazon, but nothing like a black round seal is coming up! Feel so stupid!

Heedtheadvice

There are generally two types that are not solvent welded (that one is not what you describe).
1Those with the black bit as 'rubber' sealing ring that gets compressed into the pipe and the inside of the fitting, tightened by the screwable ring -the gland nut. The blue washer prevents the clamping ring from distorting the black sealing ring and reduces friction inside the coupling and ensures even pressure on the sealing ring.

The sealing ring is essential and comes in various sizes. You need one of the correct size.
It is essentially of the same diameter as the blue ring such as 32 or 40mm pipe sizes. Take your blue ring into your DIY shop to get the pipe size matched.

There have been a few slightly different sizes historically and the sealing ring could be ever so slightly smaller.

See the following page for a picture and info under the 'compression' heading https://www.diydata.com/plumbing/waste_pipes/waste_pipes.php

2 A simpler push fit that has no compression threaded gland nut but is just sealed by a rubber 'o' ring. That also needs to be correctly sized for the pipe. Pipes and the 'u' bend fittings usually have their sizes marked (and sometimes the manufacturer-that can make a difference so best get compatible bits!) .

For both types the male and female parts need to be of the same type and compatible sizes. If by any chance someone has got them mixed up you can get the correct bits at the usual DIY outlets. For a bathroom sink it is probably the 32mm diameter pipe and you need to get parts or the sealing ring to suit your pipe size. If in doubt just measure the pipe outside diameter.

Addition: for searches include the terms sink waste and trap rather than ubend!