Sewage smell in kitchen

[padsi1975]

Hi
Had a flat roof replaced last week. Day after they finished we woke up to an unbearable smell in the kitchen (located under flat roof). They came back and ran a hose down soil stack. Don't know why as you can't see where it joins mains, it's under our grass apparently. Had doors open for hours. Smell went away and didn't return until this morning. I didn't open windows as wanted plumber to be able to smell the stink but by time I left for work smell had dissipated. Has anyone any suggestions? The intermittent nature of the smell has me stumped. Help me please!

please post photos of where the soil pipe is.

It ought to rise up and be open at a height above the opening windows. There is a possibility that it used to go up through your roof and the roofers cut it off or damaged it so it is venting inside the building.

On old houses the soil pipe is attached to the side of the house and you can see it rising above the gutters. On new houses it is in a duct in the corner of the bathroom, and usually runs down the same duct in the corner of the bathroom below.

Some people don't have the soil pipe venting into the open air, they have it terminating in the bathroom with a nominally non-return air valve on the top. These are noted for jamming and allowing sewer smells into the room.

Thanks so much, I will take photos and post.

Update: after much investigation it turned out that pipe connected to soil stack (under kitchen floor) had many cracks. Drains people spent 3 days digging up kitchen floor and putting some sort of liner into pipe. They finished last Wednesday. They said give it a week as smell would linger as sewage water would have leaked into ground and would take awhile to dissipate. Well, it's been a week and I can still smell sewage. Does anyone have any idea how long the smell might linger? At what point do I ask drains people to come back and take another look? Thanks a lot.

Hi, giving this a bump in the hopes there are some experts out there. Thanks.

Hi Op,

Almost exactly the same thing happened to me, only it was after our new bathroom was fitted. The plumber must have knocked the soil pipe, which then fractured at the join located just under the kitchen floor.
Unlike you though, we didn’t discover it for a couple of weeks, so by the time we realised what had happened, a fair amount of waste had escaped!

We too, ended up pulling up the kitchen flooring, digging the goo and contaminated soil out and replacing the ancient pitch fibre pipework. Horrible job but the smell went really quickly once the ground wasn’t getting leaked into any more.
We’d had a horrible infestation of drain flies too, as a result (I’ve posted about this before!) which was why we removed the sewage soaked soil.
I guess the smell will just fade over time as it dries out.

Hope it gets sorted soon!

have you got a wooden floor with a void beneath it, then concrete or earth where the drain is buried?

Or have you got a concrete slab floor which is contaminated with sewage?

Hi, and thanks for responses. I have a wooden floor. Concrete underneath. Pipe buried in the concrete.

Drain flies???!!!

Yep! Little furry things that are easily mistaken for fruit flies. They love stagnant water and feed off drain slime and sewage goo and the like.

Tricky to get rid of unless you totally remove their food source, hence our digging about half a ton of soil out!
I could write a book!

If you have concrete, you’ll be fine 😊

RumDo, that sounds absolutely revolting! You poor thing. Suddenly a smell doesn't seem so bad......

It was revolting for poor DH who did most of the digging!

The flies were pretty grim, it’s true, but they don’t carry any disease so that’s something!
They were everywhere and no matter how much hoovering/trapping/spraying I did, they just kept coming. They’re most active in the evening, so every day around 5pm they’d descend. Every kitchen surface would be covered, then they started spreading throughout the ground floor, then upstairs.
In the end, we dug out the soil, and part laid a new laminate floor, leaving a little gap to place smoke bombs in the cavity

I have a wooden floor. Concrete underneath. Pipe buried in the concrete.

If you have a void under the wooden floor, it should be ventilated with airbricks on at least two sides of the house so there is a through draught to keep it dry.

If so, make sure they are clear, and then you can seal any gaps in the floor that the smell is coming up through. These are most likely to be in the kitchen, under and behind the kitchen units, where fitters like to hack holes for pipes and cables with axes and chainsaws, confident that when the units are in place nobody will see them.

If the airbricks are choked with cobwebs and dust, you can clean them out. If they have been buried under paving or flowerbeds it is more difficult. If they have been blocked by extensions and conservatories, it is possible to cut a hole through the brickwork where it is accessible and add a new airbrick. One every two metres is not too many. A periscope vent can be used if the ground level has been raised above the void.

Posted too soon, sorry!
Smoke bombed every 10 days or so for about 6 weeks, and spent hours sealing up gaps in the skirting and any other exit points. Then I used Indorex (BRILLIANT stuff!) on all the areas around the source, and eventually....gone!

Thanks PigletJohn. There are two airbricks outside on the patio. I will check that they are clear tomorrow. The wooden floor has not been repaired yet (where they had to cut through it). I just laid the square of floor back on top of the concrete. Would the smell come up through concrete? Any idea how long we might have to live with it? The smell started at start of September so there has been at least three months of leaking.

Oh my God RumDo, that sounds like a full time job!

I'm just worried that the repair didn't work or the fractures pipe wasn't actually the source of the bad smell. My bathroom sink was gurgling like mad until the repair, not a peep now. But this morning the shower started gurgling like crazy and the bathroom has smelled like drains/damp for last few mornings. Could be a coincidence I suppose. AND the kitchen sink (different pipe to the one that just got repaired) is draining very slowly. The pipes seem very unhappy in general!

that suggests a blockage.