Strange sewage smell coming from behind kitchen sink cupboard

[Steven Southern]

So now everything is unblocked. How long would it normally take for the smell from behind the sink disappear. It’s not coming from the plug hole.

 

[Chuck]

So now everything is unblocked. How long would it normally take for the smell from behind the sink disappear. It’s not coming from the plug hole.

How long is a piece of string?

Unless you have some way of blasting fresh air through all the voids where the smell is lingering it will gradually diminish and lose a certain proportion of its concentration day-by-day.

My worry, and I'm always a pessimist when it comes to drains, would be that the root cause of the smell is a leaky drain and the blockage forced sewage out through the leak into the surrounding ground. If this is the case it will take as long as it takes for the ground to dry out.

If I owned this problem and the smell hung around for more than a week or so, I'd be considering having a CCTV inspection and a leak test. As I said, I am a bit of a pessimist, but a builder that left the drains in the condition you found them in is IME likely to have cut other corners. In these days of 'polluter pays', you really don't want to have a foul drain leaking into the ground for years.

 

[WC1]

Hi Steve, has the manhole beeen cut to let in the white pipe on that picture? If so then the blockage filled up the manhole until it found its way out through that opening!!

 

[Steven Southern]

Hi Steve, has the manhole beeen cut to let in the white pipe on that picture? If so then the blockage filled up the manhole until it found its way out through that opening!!

Yes it has been cut although that’s the only clean bit. It’s a gas pipe apparently.

 

[WC1]

U nfortunately there's definitely a bit of a problem there . It's just not possible to cut into an insepction chamber in that way. Debris will always be falling in and blocking the pipe (aided by rats), sewage will then be leaking out into the ground causing a potential health hazard.😳 It will need sorting.

 

[Pickwickpick]

If that's soil that is visible between the white pipe and the black plastic you might want to think about sealing it to avoid any soil getting into the drains and causing another blockage

 

[Pickwickpick]

Also just another thought you want to make sure that whatever you sell it with rats can't get through (could get some wire mesh I'm there) as they're drawn to sewers and could cause even more problems.

 

[WC1]

As the integrity of the I/C has been breached significantly and the gas pipe has been exposed... I'm out... Good luck

 

[Steven Southern]

So. A week or so has past and we’re waiting for the smell to disperse. A strange update that the smell is mainly concentrated to behind the sink and totally goes when the window is open. (But it’s not going out the window) comes back minutes after the window is shut. Strange.

 

[WC1]

Airflow is coming in the open window and pushing the smell back down behind the sink where there is an opening down to where the sewage leak is - the opening from which the sewage usually smell issues. Have you lifted the lids on that run again yet? I know I said i was out but I can't not see a problem through to the end.

 

[Steven Southern]

Yes I’ve been and looked today in the light. All appears well. Could the fact that the lid isn’t fully sealed (we’re waiting til the new year for the flagging to be done) be a contributing factor with pushing the sewage smell up the drains? With the air getting in from the lid. Cheers for the help.

 

[Pickwickpick]

No it won't be that even with the manhole cover removed it shouldn't create any smells in your kitchen. When you say the smell is behind the sink, do you mean at kitchen counter top level, or in the cuboards underneath?

 

[Steven Southern]

No it won't be that even with the manhole cover removed it shouldn't create any smells in your kitchen. When you say the smell is behind the sink, do you mean at kitchen counter top level, or in the cuboards underneath?

It appears to come from behind the trap where it would go outside but obviously it goes into the false wall now.

 

[Pickwickpick]

Any chance of a picture? Sounds to me like its an issue with the trap or the pipe work that joins it. Is there any smell coming from the sink hole?

 

[Steven Southern]

Any chance of a picture? Sounds to me like its an issue with the trap or the pipe work that joins it. Is there any smell coming from the sink hole?

There’s no smell from the sink hole.

 

[Chuck]

we’re waiting til the new year for the flagging to be done.

Don't complete the flagging until you had the gas pipe relaid in a position that complies with the regulations. Underground works are not my thing, but I am sure that you are not allowed to have a gas supply cutting though an inspection pit in the way yours has been.

You will need to follow the 'move a gas supply' procedures published by your network supplier. From memory of a job I've only dealt with once some years ago, the gas pipe will need to be made of approved materials and marked with warning tape, and end up 18 inches deep in a trench surrounded by (6 inches?) sand and no closer than 12 inches to other services.

Whoever did your current work, IMO, should be prosecuted. A rat will happy chew through that pipe and fill you drains with gas. If you knowingly leave it like it is, IMO, you should be prosecuted too.

Once the gas pipe is relaid safely, as I said before, you need your drains properly leak tested. It wouldn't surprise me if all the new stuff needs to be excavated and redone by someone competent.

 

[WC1]

Your water board will have a list of underground contractors who will be able to help. You might want to look at something like household insurence to help you make some sort of claim against the guys who left it like this state, scandalous, IMO. If someone made an honest mistake I'd usually say get them back and give them a chance to put it right, but not in this case. I'd keep lifting the lid every few days because you won't know if it's blocked because the waste will just leak out by the gas pipe. (which is one reason why you can't just cut into an I/C) - and it will block again because of the soil falling in at the breach. Look on the bright side, you found it, and you can put it right rather than building contol, the water board or some other body finding it - that could have caused you serious issues. You've come to the right place to get some input and you should be able to recover the cost from the other side. Merry Xmas to All and best wishes for the new year, WC1