External sink/wm waste and downpipes - lubricant? Sealer?

30 Mar 2011
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United Kingdom
I'm about to replace some 68mm downpipes and elbows, and also the external waste pipes and elbows from my sink and w.m. I see that there are lubricants etc for sale. Do I need any kind of lubricants or adhesives to hold the pipes and joints together?


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That all depends on the makes and systems you intend to use.

Frankly it does not sound as if you have the skills and knowledge to do that kind of work.

Basic plumbers who do that kind of work are not always that expensive!

Yes, but there are several different systems of waste pipe.

Some are push fit and others compression and others solvent weld.

You need to choose what you are going to use first and then ask specific questions about a named product.

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Most 68mm is straightforward socket/spigot and don't have any mechanical seals so just make sure any pipe is cut straight and clean off any burrs. If any of the pipe run isn't running vertical then some guttering sealant can be useful around the socket joins once connected to avoid any backflow from the joint. Needs to be clipped accordingly.

You can use solvent or ring seal components but as Tony mentions it depends on the system type/make that you intend to use.
Thank you Tony and Rob for giving me helpful answers.

I didn't have much choice in where I bought the stuff, not having a car or any builders' merchants in easy reach, and I am having a delivery from Wickes anyway, so I chose all the stuff from them. I measured all the pipes carefully and they turned out to be three different sizes - 68, 40 and 32.

All the stuff I bought is from the WICKES BLACK ROUNDLINE range, for example this:


I have two elbow joints to fit. They look different from the ones I am replacing, which are big and corrugated - and, I might add, stuck hard! Might have to saw them off. Oh, and what kind of saw would you gents favour? A hacksaw or an ordinary big saw? I also have a jigsaw, which I enjoy using when allowed!


I assume you are trying to connect everything to that gulley in a neater fashion . Can you post a picture of the wall where the larger pipe originates- does it come from a bathroom ?
It comes from the guttering on the back of the ground floor of the house Nige.

I've stood and stared at the photo above trying to work out if there is some way to make it look less messy. All I came up with is putting a proper elbow at the end of the 68mm pipe instead of the shoe end, and thus directing that pipe straight down into the drain.

The pipes are washing machine (r) and sink.

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OK, if the joints are stuck hard then it's probably been solvent welded, cutting would then be the only option. The trick is to cut the pipe square, which can be tricky. A normal saw is probably easiest, a hacksaw tends to wander. You do get plastic saws, like normal wood saws that have finer teeth and will give you a cleaner cut. Remember to clean up the cut with sandpaper after.
Take a piece of paper and wrap it around the pipe as a guide for keeping the saw straight.

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