Quesiton: Unusual toilet waste

I am refitting my bathroom and found an unusual setup when I pulled out the old toilet and floor. The toilet waste was not routed "out the wall" so to speak but instead it came out a 90º pan connector and then a 87.5º bend under the floor - then there was a boss coming off the pipe under the floor and they had routed 32mm pipe up through a wall cavity and eventually through the roof. I don't think this is compliant so want to change it out - however I do not want to run directly out the wall behind the toilet as it is now to be located on the front wall of the house and the main soil & vent stack is around the side of the house. Hence my plan was to fit a branch below the toilet and take a pipe up to a durgo then box that in. The toilet is on it's own indepenent branch of the waste system i.e. no sinks or baths etc. tie into the 110mm before it ties into the main soil & vent at the lower end of the fully vented stack that everything else ties into around the side of the house. Hence I am thinking that the flood level of the system will only be the top of the toilet U-bend (i.e. I can have my durgo mounted quite low and hence hide it in the corner under the stairs).

Does this sound reasonable? Any help appreciated!!

If you fit an AAV instead of an open vent, without LABC approval, then you'll be making your installation less compliant, not more.

Hmmm yeah was just reading the "document H" and I suppose the installation could be classed as a branch ventilation pipe - although the high point of the vent does not tie into an existing stack it just goes up through the roof space. Thanks for reply has made me think again before ripping this out!

Although 32mm is small bore, AFAIK it doesn't automatically contravene.

Recently a BCO approved an installation where I fitted a 50mm pipe going from a 110mm 1st floor horizonal branch to a roof tile vent. This was several years after the original builder had failed to fit any vent at all - the house had been ponging for all those years.

Check this out:



Bold lines are 110 mm soil & vent, narrower are 32/40mm drains/vents. The previous install routed the 32mm to a tile vent as you describe, I was going to put a durgo in as shown in red (above highest flood level in system)and take away the 32mm branch vent, leaving the high point soil vent outside.

You reckon the 32mm tile vent will be good enough? The old pan I took out drained very slowly, could this be due to the 32mm vent or just the "super seventies" design of the pan?

How long is the "horizontal" 110 part?

looks ok to me it is only a secondry vent i would leave it .
also regs say durgo above lowest water level ie: cistern height .. does this help at all it is very early and i am very tired.

rosst3mp, you're clearly quite clued up on all of this, but I get the feeling that you regard an AAV (e.g. Durgo) as an alternative to a vent, but it isn't - they have different functions and purposes.

The confusion commonly arises because AAV has two meanings; in the context of boilers and heated water it means "Automatic air vent", but in the context of soil and drainage it means "Air Admittance Valve". A soil AAV does not serve to vent under positive pressure, therefore is not a replacement for a vent.

Technically, depending on distances, replacing the secondary vent with an AAV might not cause problems, but your LABC has the final say so on this, and they ought to consider the available vents in the locale (i.e. neighbours dwellings) before deciding.

THANKS ALL FOR COMMENTS!!!

ChrisR said:

How long is the "horizontal" 110 part?

Click to expand...

About 2m on a down slope under the ground floor of my house (solum area).

Softus said:

rosst3mp, you're clearly quite clued up on all of this, but I get the feeling that you regard an AAV (e.g. Durgo) as an alternative to a vent, but it isn't - they have different functions and purposes.

Click to expand...

I do not mean to come across as bolshy at all here - I am looking for advice - but I do know they have different purposes and that a Durgo is an air admittance valve, although I thought that (looking at the sketch) when the toilet is flushed a slug of water would create a negative gauge pressure in the run immediately downstream of the pan - hence the need to admit air near the pan. If however there was some back pressure from other equipment in the system or indeed the sewer it would vent off via the vertical stack on the right of the sketch.

Softus said:

Technically, depending on distances, replacing the secondary vent with an AAV might not cause problems, but your LABC has the final say so on this, and they ought to consider the available vents in the locale (i.e. neighbours dwellings) before deciding.

Click to expand...

NB This is a single detatched house - and I am looking to complete significant renovation work and want to keep it compliant. If this is technically OK then I can argue the case with the council to fit the durgo rather than cut a chunk out of the front of a period house!

On another front I got home from work to find the plasterer had made an absolute hash of a job so am going to have to get it all re-done!!!

I would say you have a good case to argue.....period properties can be a nightmare to get plumbing in/through ..I`ve done a few here in Sussex...hope you`ve got a sturdy timber framed one it`s the pile of flint ones that deprived me of sleep