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May 27, 2019
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Hi all,

I've got a 110mm soil pipe that rises out of my kitchen floor, under where the sink will be. How do I plumb in a 40mm waste (from kitchen sink) and also waste from a dishwasher into the top of this pipe.

(Currently I have a wad of rockwool plugging the 110mm, to stop gas/smells coming up. This soil pipe drops down vertically (through screed and concrete slab), then tee-ing into the drainage below.)

Is some sort of rubber reducer on the end of the 110mm the way to go? It'll need a trap above, but will the reducer definitely keep a good enough seal on the 40mm pipe running down through it to keep out gases?

And how should I fix the 40mm to make sure it doesn't move and deform the reducer enough to break the seal?

Thanks!
 
F84D0E8A-3F8E-4B17-90C1-E503E53BBF7E.jpeg
If you’re worried about movement you could use this solvent weld version.
 
You can get versions to take two pipes into if it's required

Only found one double online that was a pair of 40mm (most seem to be 32/40):
40/40 double drain connector
Which is pushfit. My bit of vertical soil pipe is pushfit I think, but the exposed end does not have a seal.

Any one thought that the 110mm discharge stack might need venting ????
I don't care what McAlpine say IMHO push fit fittings like these are a bad idea internally as they are unlikely to withstand any back pressure should there be a blockage.

Ok, sounds worth taking into account. This soil pipe tees into the drainage under the house. The tee is between the base is the SVP (middle of house, vented through roof) and the sewer running under back garden. For pressure to build up to worrying levels there would need to be a blockage between the tee and SVP right?
 

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