Underground Drainage / Waste and soil connections

4 Nov 2009
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United Kingdom

I have recently replaced the underground foul drainage to my house with pvc pipe as the clay pipes were damaged. See photo.

I now also want to replace the cast iron stack with a pvc stack (which currently is coupled with a plastic section as a temporary measure).

Ideally I would like to connect my bathroom sink and bath waste pipes into this new plastic stack instead if them connecting to to the plastic hopper via a seperate down pipe as they currently do so.
Can you connect bath and washbasin waste pipes into a foul stack beneath the connection for a WC ?

I would also like to connect both my kitchen sink waste and condensate pipe from the boiler into the plastic hopper shown in the photo.
Is it possible to connect these pipes underground for a neater result i.e. cutting out the holes in the side of the hopper? shown in the second picture?

Any advise is gratefully accepted and I look forward to any suggestions?


Rick 85
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bath and washbasin into soil stack = yes

but at least 200mm below the centre of the wc connection to avoid any nasty effect on the traps etc.

you could cut the kitchen and condense below ground level, but still above the water in the trap i suppose, a blockage would lead to backing up of the water although i can't really see how this would happen, personally i cut a hole in the grid and pop the pipe in about 25mm through the grid. prevents splashing and looks neat enough to me.

in fact the hopper you show appears to have a cutout in the mould, so a rubber adaptor plug to suit and it should work fine.
Thanks for the advice. I was guessing the circular thing on the side of the hopper was purposely to cut out a hole for a pipe. But not sure?
The boss on the side of the gulley hopper is for waste pipe connections. Purely depends on ease of installation, if the wastes are at the wrong angle it may just be easier to drop them into the top. Pipes should discharge under the grid, but above the water level in the gulley.
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What is the best way to cut the hole out?
Do I need some sort of additional insert or do you simply put the pipe through loose?

As an alternative, could I also put the kitchen sink waste into the soil stack at low level (ground floor)?

Thanks again.

Rick 85
Hole cutter. Or lots of patience with a padsaw and file!

It may need a boss adaptor, depends on size of boss, but problem I can see is you currently have push fit waste. If the boss is 40mm, then the waste pipe is same size, but push fit pipe cannot be solvent welded to the boss to seal the joint.

You could connect waste to stack, only issue there is if the drain blocks then contents of upstairs W.C. have been known to reappear in the sink..... Personally I'd drop it into the gulley as current set up unless you need to change the sink waste.

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