Trying to Understand my Waste and Soil Pipe Plumbing

[Hugh Jaleak]

I'd lift this any any other covers on the property/surrounding area before doing anything else, and check the drainage system is free flowing. Any sign of standing water and/or build up of waste in the channels/on the benching/sides of the chambers is a sign of an issue, and shouldn't be there. Has anything heavy (e.g. a skip or large vehicle) sat on or passed over where the drains run, or any signs of ground movement? A properly functioning drainage system should be self cleansing, and any odours/positive pressure escape via the Vent Stack.

To be honest, I think the chances of any noticeable amount of odour entering the building from a poorly fitting manhole cover via an airbrick are virtually nil, if there is an odour internally I'd be looking very closely at the plumbing before doing anything else.

 

[endaxi]

I'd lift this any any other covers on the property/surrounding area before doing anything else, and check the drainage system is free flowing. Any sign of standing water and/or build up of waste in the channels/on the benching/sides of the chambers is a sign of an issue, and shouldn't be there. Has anything heavy (e.g. a skip or large vehicle) sat on or passed over where the drains run, or any signs of ground movement? A properly functioning drainage system should be self cleansing, and any odours/positive pressure escape via the Vent Stack.

To be honest, I think the chances of any noticeable amount of odour entering the building from a poorly fitting manhole cover via an airbrick are virtually nil, if there is an odour internally I'd be looking very closely at the plumbing before doing anything else.

Thanks for the advice, Hugh. No lorries or skip that I know of and everything looks sound superficially. This transient external odour has been there since we moved here a couple of years after the house was built. It only happens occasionally, is not really strong and doesn't hang around too long. The toilets and drains to this stack all run well and the stack itself is vented through the roof.

I've just emailed a plumber about the AAV on the other stack so I'll talk to him about it and will certainly lift the cover to see what's happening. Thanks again and I'll keep you posted.

 

[endaxi]

Well, I lifted the inspection cover and it was as clean as a whistle down there and had hardly any odour. I flushed the downstairs toilet and it rushed through no problem. It's then only about a two metre run to the road where I presume it joins the main sewer. I still think that the odour gets pushed out somewhere when the pump at the bottom of the road sends sewage up the hill to join the main sewer and then run back down again. Neighbours across the road said they get an odour outside their front door occasionally too.

Anyway, there was some dried/cracked/perished sealant under the cover where it sat in its recess. I remember this cover getting lifted many years ago by the water company and just put back with no fresh sealant so it's possible the odour was escaping from there I guess. I scraped all the old sealant off, cleaned and dried the mating surfaces, applied a layer of Vaseline, put the cover back then filled the gap with a bit more Vaseline. Let's see if we stay odour-free.

No word from the plumber about fitting my new AAV at the back yet though.