Leaking boss waste (not strapped)

14 Nov 2009
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United Kingdom
Hi all,

I have recently re-furbed a tired bathroom and am quite impressed with the result. :eek: However i have just noticed a leak which eminates from the basin waste / soil stack boss connection. :(

The boss is an 'in-line' version ie it is part of the stack and not a strap on version.
The leak seems to occur when the tap has been switched off and seems to work back up the underside of the 32mm waste pipe.
The waste is pushed into the boss and is supposed to be sealed by a rubber O-ring and plastic grommit of the boss.

This is exactly as the old system was set up, I simply pulled out the old pipe and pushed in the new so i don't understand why it is now leaking? :confused:
I am fairly sure the new and old pipe are the same diameter however the fitting / connection isn't particularly tight.
Is there another gasket/O-ring/washer I can purchase to solve this or is it a bigger problem?? :confused:

Many thanks in advance for any advise. I appreciate there are similar posts but they all seem to be about the strap on version..
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pull the pipe out and check the o ring hasnt been squashed or shoved out all together.

give the pipe a shampfer with a file and add a bit of silicone grease to help it slide in.
pull the pipe out and check the o ring hasnt been squashed or shoved out all together.

give the pipe a shampfer with a file and add a bit of silicone grease to help it slide in.
Talk for yourself, big boy ;) :eek:
Thanks BingoBongo,

It slides in relatively easily without grease (steady Dextrous), which I think may be the problem??

The O-ring appears fine. I've just noticed the Boss has 36mm stamped on the side and i'm using a 32mm pipe could this be why its leaking?? Pipe too small?? Or is that just a ID / OD thing??

It seems like I need a thicker O-ring to tighten the joint / connection any ideas?
Is it a 'Terrain' boss? They are different, using a plastic socket with an 'O' ring to make the seal, rather than the rubber 'plug' type.
Hi Hugh Jaleak,

It is a Marley Push fit Boss, but I would say your description of the plastic socket and O-ring is what I have rather than the rubber 'plug' type.
Which is why I had concerns over the adaptor suggested by Dextrous not sure if it would fit the Boss I have??

Similar to link, single version.



Is the pipe a snug fit in the boss?

I say that because solvent weld waste and push fit waste has slightly different circumferences. Can't remember which is bigger.

Just a thought.
Yes, the Terrain version is very similar. Not sure if you'd get away with solvent welding a bit of pipe into it? Only other suggestion is filling it with silicone or using some denso tape, neither ideal, but I dont suppose replacing the boss pipe is an option?

Might be possible to obtain a new boss adaptor from Marley and 'graft' the O rings and plastic collar over but thats not guaranteed to seal. I had one similar, totally inaccessable. The guy wasnt keen to pay to have anything done so I left it leaking under his floor.....
How do you mean 'graft' the O-ring and collar over - Just swap them out??

I don't fancy it but the silicone or denso tape may be the last resort! :cry:

Whitespirit66 - It is reasonably snug but not as snug as i'd like which i think may be part of the problem?
I may see if I can get a thicker O-ring to see if that helps??
Stack and waste pipework are all push fit and Marley so should be compatible? However, as mentioned above, the boss does have 36mm stamped on side and i'm using 32mm pipe - could be why?? Unless its a OD / ID thing??

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