Kitchen Sink Gurgling

[creative-2008]

We moved into a 1st floor flat, about six months ago, in which the sink gurgles about 3-4 times a day. Sometimes a sickening sulphur / egg smells joins the noise, to the extent that we want to leave the room. Sometimes it happens just after we've had the washing machine or sink running, but just as often we haven't used the water for a good few hours.

The block of flats is about eight years old and prior to is moving in, our flat was unoccupied for about 2-3 years. We have a double sink, the smaller side bit has an overflow. We rarely use the smaller side sink and until I ran water through the overflow today, I don't think water would have passed through it for several years. The dishwasher and washing machine also connect to the same set of pipes.

I've disconnected and cleaned two of the PVC pipes under the sink. I've attached a labelled photo of the set-up, and what I've done. (Apologies if anything I've labelled is obvious to the reader.)

1 - This wasn't blocked but was lined with a stinky black gunk, which I removed

2 this comes from the main sink. Gunk also removed

3 connects the side sink overflow. It's bound by adhesive to the side sink. Haven't removed it

4 Plug in side sink - haven't removed

5 washing machine

6 dishwasher

Since I reattached the pipes I've also sent bleach down, hoping to kill off bacteria and reduce the chance of smells. I'm also planning to send down baking soda / vinegar to clean them further.

Something googling threw up was replacing part 1 with an anti-vacuum equivalent. Is there any sense in that?

Any advice would be greatly appreciated, and I'm happy to post further photos if needed. Thanks.

 

[steadyon]

1. The flexible hoses to the washing machine and dishwasher (your number 5 and 6) don't appear to rise to a level immediately below the work surface and then drop to their spigots above the trap. There is therefore likely to be water (stagnant?) trapped in these pipe. These could cause the gurgle and smell.
2. The white plastic pipe labelled 8 is most likely the condensate drain from the boiler. Some boilers discharge the condensate as a slug of water, rather than as a continuous trickle. This could cause the gurgle. It could also be "pulling" the water from the trap (your item 1) which would allow foul smells from the sewer back into sink. Its not very likely given that its a small pipe discharging into a larger one, unless the larger pipe is partly blocked.
3. There may be an issue with the drains beyond the point where the white drain pipe disappears through the back wall.

I'd suggest you first try re-routing the washing machine and dish washer waste pipes (grey, corrugated) so that they rise as high as possible before falling back to their spigots.

If either symptom remains, you need to investigate the drainage system beyond what is visible in the picture.

 

[rpm]

What is pipe 8 from?

 

[townfanjon]

What is pipe 8 from?

Boiler condensate pipe pal

 

[rpm]

Then it`s most likely a syphon problem going on there.

 

[creative-2008]

Cheers for the replies.

I was guessing that 8 was coming from the boiler, but couldn't be sure.

So essentially there are 3 scenarios.

1) the gurgling is being caused by our washing machine or dishwasher, and if so it's realistic to fit that.

If we didn't use either for 3-4 days, and the gurgling continued as before, would you rule that out? I'm trying to think of a way of working it out before I go to the trouble of cutting into the back of the cupboard to move the flexible waste pipes.

2) we have a blockage somewhere in our flat. And knowing that we don't have any drainage problems and I've taken most apart already, the blockage is below the water trap.

That I can tackle / eliminate by plunging etc

3) the blockage potentially lies with a neighbour or in a communal section of piping.

 

[johnduffell]

If there's glugging and a smell when you're not doing anything, that points to positive pressure in the drains pushing smells out.
Is there a vent pipe on the roof? If there's a partpartp blockage or the pipe is full of water and it's on a branch without a vent, you can get air forced through the traps into the room

 

[Gasinspect]

Not the real answer, but worth putting in a tee with anti vac air admittance valve. Some building inspectors asking for them now. could be a nightmare to track down proper venting.