Soil pipe ventilation

thomboross · 29 Nov 2023

Alright folks.

Hopefully, someone can help in regards to venting my waste pipe from a downstairs cloakroom toilet.

It comes straight out and down as in the image and the white pipe is my new drainage from the kitchen, however it's not vented.

My toilet bowl is filling up and returning to normal slowly so there's no pressure within the pipe to push this out. It's not blocked etc as I've checked all this.

What would be the best way to vent this to allow the air through?

Cheers for your help.

88v8 · 30 Nov 2023

What you have there is an ingenious but horrible bodge. That corrugated thing.. looks like it was borrowed from a fan ducting. And is it really on the wonk or is it the photo.....
It's only because the fall is so short that it doesn't suck all the water from the bowl.

It needs a stack pipe run up the wall, on the outside, as per usual. The open top of the stack pipe will provide the air vent. A bird guard will keep the pigeons from nesting on top of it.

If you take the pic to your local plumbers' merchant, when they finish falling about they'll be able to provide you with the bits to fix it, then you just need a ladder.

The vent pipe for a two-storey house must be not less than 75mmm diameter. The open top of the stack pipe must be at least 900mm above any opening window.

thomboross · 30 Nov 2023

88v8 said:
What you have there is an ingenious but horrible bodge. That corrugated thing.. looks like it was borrowed from a fan ducting. And is it really on the wonk or is it the photo.....
It's only because the fall is so short that it doesn't suck all the water from the bowl.

It needs a stack pipe run up the wall, on the outside, as per usual. The open top of the stack pipe will provide the air vent. A bird guard will keep the pigeons from nesting on top of it.

If you take the pic to your local plumbers' merchant, when they finish falling about they'll be able to provide you with the bits to fix it, then you just need a ladder.

The vent pipe for a two-storey house must be not less than 75mmm diameter. The open top of the stack pipe must be at least 900mm above any opening window.

Thanks mate.

yeah, it's not ideal, no idea when it was done, think it was back in the 80s.

That's what I was thinking but wasn't sure whether it could be temporarily vented as is for now.

Cheers though!

pcaouolte · 30 Nov 2023

If the toilet has been working for 40 years with that bodge, something must have changed to stop it working now. Usually a blockage.
Is the new pipe from the kitchen also a bodge, I cant see any evidence of a strap boss? Is the kitchen pipe sticking into the waste pipe from the toilet and partially blocking it?

thomboross · 30 Nov 2023

pcaouolte said:
If the toilet has been working for 40 years with that bodge, something must have changed to stop it working now. Usually a blockage.
Is the new pipe from the kitchen also a bodge, I cant see any evidence of a strap boss? Is the kitchen pipe sticking into the waste pipe from the toilet and partially blocking it?

I mean I can't say if it was working properly. I ripped it all out last year when I got the place. However, when I installed the new toilet and sink it was flushing perfectly. It's genuinely only in the last couple of days I have noticed the water rising in the bowl and slowly returning to normal.

The only thing that changed in the last couple of days was that I ran the dishwasher for the first time to test it.

The drainage from the kitchen is all new and the connection onto the soil pipe is flush so no blockage from that. There's no immediate blockage at the toilet end and I have fed about 5 meters of piping down the soil pipe with nothing blocking it.

88v8 · 30 Nov 2023

thomboross said:
It's genuinely only in the last couple of days I have noticed the water rising in the bowl and slowly returning to normal.

That suggests that there's pressure in the sewer from other toilets upstream. Perhaps a neighbour has added something, or new builds... A vent would disperse the pressure, as it is, it's trying to vent through your loo.

thomboross · 30 Nov 2023

88v8 said:
That suggests that there's pressure in the sewer from other toilets upstream. Perhaps a neighbour has added something, or new builds... A vent would disperse the pressure, as it is, it's trying to vent through your loo.

would it be possible to add a vent from the side of the soil pipe, at the highest point on the vertical as a temporary fix for now?

88v8 · 1 Dec 2023

thomboross said:
would it be possible to add a vent from the side of the soil pipe, at the highest point on the vertical as a temporary fix for now?

Yes.
Bear in mind that pongs will emerge from the top of the vent, so it needs to terminate someone out of range, so to speak.

denso13 · 1 Dec 2023

thomboross said:
would it be possible to add a vent from the side of the soil pipe, at the highest point on the vertical as a temporary fix for now?

Just add an external AAV (Durgo),

88v8 · 1 Dec 2023

denso13 said:
Just add an external AAV (Durgo),

But... a Durgo only prevents the water seal being siphoned out of the pan when the loo is flushed.
It does not vent back-pressure, which is what the OP is reporting.
The stack pipe would still need to be connected to a vented stack.

Madrab · 1 Dec 2023

The stack and drains need to breathe and must be able to release both positive and negative pressure. If everyone on the shared drain run has added AAV's (durgos), then as suggested the drain cannot vent, therefore positive pressure is getting trapped stopping the toilet from draining properly. Are you on speaking terms with the neighbours? noticed any work getting done? Ideally whoever is situated at the head of the drain run should have at least one stack venting to air.

To test you could add a branch onto that and a small stub of pipe and certainly remove that flexi section and see if that alleviates the problem, if so then you need to have a chat with the neighbours as someone else may have changed their setup, being the last one that had an open vent.