New WC connection to private sewer

4 Sep 2019
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United Kingdom
Hi all,

I'm converting a pantry into a downstairs loo/shower room.

The sewer runs along side the wall where the wc pipe will come out and into a stub stack. I have excavated a hole to the sewer pipe, which is below the foundations and 16.5 inches (centre line) from the wall - see image. The 7" sewer pipe is currently laid on earth. I will be putting a 160mm, 45 degree T into the 7" sewer pipe which reduces to 110mm" on the t itself. I have three questions:

1. Do I have to have a flat invert bend that connects to the side of the sewer line or can I position the t so that I run the 110mm stack at an angle so that I don't have to dig too close to the foundations.

2. Once I've made the new connection do I fill the trench with pea gravel or concrete up to the bottom of the foundations?

3. Does the stub stack need a rodding point, or can I simply go through the top of the stub stack if necessary?

Any advice gratefully received.


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You will be better off having a small plastic IC in that location unless you can show that the junction can be rodded from both directions elsewhere.

The hole will need to be about three times the size it is now so that an angle grinder can be used to cut through the SG pipe etc. Not a particularly difficult job but lots of digging and getting rid of spoil
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Are you sure that sewer is private? I'd be surprised if a 6" pipe is just serving one property!
I'm not sure whether that is a 6" salt glaze pipe. 6" SG pipe measures about 8" across the diameter whereas 4" stuff is about 5" across.

If it is 6" bore then it is unlikely just to serve the one house although on an estate a few miles from us, they used the 6" almost exclusively. Must have had a glut of the wretched (expensive) stuff.
I'm partly going on the fact it looks like 6" and then the OP's description,
The 7" sewer pipe is currently laid on earth. I will be putting a 160mm, 45 degree T into the 7" sewer pipe which reduces to 110mm" on the t itself.

Given the size, it'll need a 450mm chamber, that's if it isn't the Water Company's asset and they want a concrete chamber....
Seems common practice now to use those bases on deeper chambers, then come up with concrete rings to form a chamber suitable for entry. Not been putting anything in now for a while, moved over to cleaning the wretched things for my sins.
Haha - big poos!!

Thanks all for your comments.

The property is a semi detached. There used to be back to back terraces at the rear of the property which were all knocked down in the 60s, so that is maybe why its so big. I am sure that only my property is connected to the sewer and the pipe can be rodded from either end of the run, so do I need a chamber or not?

I'm also not sure I'd get the new stack into the chamber given the distance between the two wall either side of the drainpipe.
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It may just require a 'Y' connection. Building Control will advise. Presumably you have made an application?

Hi Noseal,

Yes, I've made an application and called to ask their advice...they apparently aren't in the office much so I had to email them...which I did. Their response was they'll get back to me in 5 working days. By which time I'll be sunning myself (for which read painting a house) in Malta.

I can always crack on with drilling the walls for the extractor fan and toilet, but I'd rather get on with making the sewer connection and filling in the hole, rather than leave it open for the next 3 weeks, but I'd hate to do the job twice!
okay - so I hired a clay pipe cutter and have cut both ends of the SG pipe - do I have to smash out the bit inbetween the cuts - of do I just need to excavate more under that bit? - I heard the crack of the pipe - I'm hoping I don't have to recut!!

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