Smell from soil pipe

[jbaker10]

A soil pipe which drains two bathrooms and a kitchen from an upstairs appartment runs into my kitchen and empties into the main (under my kitchen) drain and thence to the sewer. Intermittently over the last two years it given off a bad smell. I got a drain contractor to check for blockages and it was completely clear (both main drain and the soil pipe). He suggested that the most likely problem was a crack in the soil pipe where it changes course from vertical to horizontal (cctv work was done but no large cracks were immediately obvious). We therefore lined the inside of the soil pipe to plug any cracks. However, the smell has reappeared and is no better. It is worst in the mornings and evenings and appears to be almost exactly correlated to toilet use in the upstairs flat. It even seems to smell of clothes washing when the washing machine is being used upstairs. I can't work out how a smell could be getting through as the whole system should be sealed (the hatch has even had silicon applied to the edges. There is no smell in the upstairs appartment. Does anyone have any ideas - could it be a problem with venting? But how does the smell get out and why would it appear so quickly after toilet use on some occasions and not at all at other times?

Please help.

Thanks

John

 

[shaggy]

The only thought I've had is if the stack was not ventilated as it should be, perhaps blocked by a bird's nest, then if your kitchen sink, or washing machine stand pipe, drains directly to the stack then the water seal is being sucked out. I once knew someone who bought a house where the stack was terminated in the loft and had been plugged by the previous owner.

 

[jbaker10]

Thanks Shaggy,

The smell is coming directly from the stack, no smells from any of the sinks, toilets, machines that drain into it. I'm stumped because the smell is coming so strongly from what should be a sealed system, at least as it passes through my kitchen. I am pretty sure the vents are not blocked, there is certainly no problem with the traps being sucked dry. I find it strange that the smell that occurs as toilets are used, etc. is so strong, to my mind that implies a large escape route for the smell when none can be found. Getting a bit detailed now but it is not the smell of fresh bowel movements, more methaney. Then some days it doesn't smell at all!

John

 

[shaggy]

I can't think of anything else that's obvious John but what is the stack made of and if it's boxed in, perhaps you can't see the defect? I assume you do connect to the stack so can you see your connections?
(I've got a lovely dog but she does fart sometimes and it does smell like a drain problem. Do you have a dog? )

 

[jbaker10]

Prior to carrying out investigation work the stack was boxed in, but now it is all visibile to ground level with no evidence of cracking, etc. The assumption I made was that it was cracked under ground with leakage underneath causing the smell. Now that the pipe has been relined professionally with some hard setting resin cracks/leaks should be impossible. I've watched a cctv of the work and it all seems seamless. no dogs to balme I'm afraid. Thanks for the input Shaggy. John