Strange sewage smell coming from behind kitchen sink cupboard

[Steven Southern]

any help would be gratefully accepted. We’ve had a single storey extension to the rear with toilet. Now we have a strange sewage like odour coming from behind the kitchen sink but not this side of the trap. The sink waste along with the new bathroom waste all now go into the soil pipe which in turn is now enclosed in the extension. The soil stack is now a plastic one instead of a cast iron one which has a cap or air admittance valve on top. This has also been shortened by about 5 feet and no longer goes through the waves and onto the roof. There is also a new manhole which I haven’t checked if it’s blocked but I wouldn’t think so as it’s only weeks old. (I’ll lift the lid and check at the weekend) once again thanks for any help. Steve.

 

[Steven Southern]

Is that standing water in the manhole?

It’s moving but slowly. That’s with the kitchen taps on full.

Quite a bit of builders crap in the drains.

Yeah I thought that. The part brick and a bit of debris fell in as I opened the lid and the water is slightly flowing with the kitchen taps on. (Not sure how fast the flow should be)

 

[WC1]

It's not really a question of how fast the flow should be. The fall on the pipe should not allow any standing or sluggish water. There's a blockage somewhere. Clear out that debris. If you've had your dinner and you're up for it, lift the next lid on the run. Watch out for Mr Rat. Enjoy

 

[Steven Southern]

It's not really a question of how fast the flow should be. The fall on the pipe should not allow any standing or sluggish water. There's a blockage somewhere. Clear out that debris. If you've had your dinner and you're up for it, lift the next lid on the run. Watch out for Mr Rat. Enjoy

So I’ve been and bought some rods today and cleared the manhole. Got some old peices of the cast iron soil pipe out the the builder obviously dropped when he was fitting the plastic pipe. Plus a few other odds n hens. Literally. Lol. Now I’ll suppose it’s how long I have to wait before the smell disperses from behind the sink.

 

[WC1]

Well done Steve! Good job. Keep an eye on it, I'd lift the lid again in a few days. If they're your fist set of rods remember to always turn clockwise. Always clockwise

 

[Sharp Point]

Couuld be the the 'builders bodge' aka an AAV? Why oh why don't they do things properly and let the darn thing breath as designed...

Builders know how to do everything..... don’t you know that YD

 

[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.