What flushpipe/connector for concealed WC cistern?

[Lobster]

I'm tackling a slight, but long-term leak around the base of our back-to-wall toilet (one of this sort of thing: It has a boxed-in, concealed cistern (like this, but an unknown model): ; and I've traced the problem to the point where the 90-deg flushpipe enters the back of the toilet, within the boxing.

Problem is evidently that the installer cut the flushpipe too short, and has extended it with a nasty bodge that isn't working well, and it's leaking. I want to either replace the flushpipe (preferably) or extend it properly. However, this pipe seems to be an odd size, and I'm struggling - it looks like 38mm OD, as opposed to 32 or 40mm for conventional waste pipe?

Any ideas how to proceed? I can see that (eg) Screwfix flog a new flushpipe; but God knows what size that is and whether it will fit my unnamed cistern:

(or ). There must be an alternative to possibly fitting a whole new cistern!

[A.Lee]

It has rubber push-fit / screw fit connectors at both ends, so will be suitable so long as it is within a couple of mm. IME, all flush pipes are the same diameter, apart from commercial ones.

[polygonum]

When I fitted two cisterns here (a number of years ago now, but recently enough to be relevant), one needed a pretty ordinary flush pipe, the other one was considerably wider at one end. Both came with their respective cisterns. Both ordinary ones sold for domestic use - Macdee and, umm, another one.

[Andrew Gabriel]

Here's a selection...

Also, here's a selection of the concealed cisterns:

[drdjdoscar]

wall toilet (one of this sort of thing: It has a boxed-in, concealed cistern (like t his, but an unknown model): ; and I've traced the problem to the point where the 90-deg flushpipe enters the back of the toilet, within the boxing. Problem is evi dently that the installer cut the flushpipe too short, and has extended it with a nasty bodge that isn't working well, and it's leaking. I want to eit her replace the flushpipe (preferably) or extend it properly. However, this pipe seems to be an odd size, and I'm struggling - it looks like 38mm OD, as opposed to 32 or 40mm for conventional waste pipe? Any ideas how to proc eed? I can see that (eg) Screwfix flog a new flushpipe; but God knows what size that is and whether it will fit my unnamed cistern:

/ljfeps6 (or ). There must be an alternative to possibly fitting a whole new cistern!

-- David

Had same sort of problem on an enclsed cistern in our house. Flush tube wa s a bit short plus the mounting of the cistern itself was a bit askew putti ng strain on the 'bung'. 38mm is simply the regular 1 1/2 inch and still readily available. Trip to local Plumbase - bought new flushpipe and bun g (called a cone) for about 6 pounds, adjusted cistern mounting. No more seepage and just relieved the leak was not at the business end.