Toilet sink smell help!

[HURDLING]

Please can someone help I have an unpleasant almost stale water smell and also sometimes a sulphur smell coming from our downstairs toilet sink. The drains have been checked and are not blocked and have been cleaned. I have tried the hot water, bicarbonate soda and all bleaches etc with no avail. Can you look at the attached photos and advise that would be appreciated. Thanks

[Geordieric]

Unscrew the bottom of the trap.
Check no cotton buds, hair etc is stuck under the plug hole etc.

Could be the water being sucked out of the trap allowing pipe smells to blow thru?
My old house it happened on a windy day to the downstairs loo

[HURDLING]

The trap has been cleaned thoroughly. Any suggestions does the plumbing work look right?

[Someone-Else]

You say the trap has been cleaned (I don't doubt you) but is there any water in it?

[sammy.se]

I have heard that vertical waste pipes can cause a vacuum because the water moves down very fast, and this causes either the water in the trap (which should block smell coming back up) to be sucked away.


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[London mike 61]

I’m not a plumber but I don’t think you would get many problems if you had this type of waste trap ;

https://goo.gl/images/h5TbZt

The one that is in your picture looks like there is no water in the trap to stop smells coming from the waste water outlet.

Mike

[Rorschach]

As others have said, check for a dry trap. Even if the trap looks like it has water in it, it might not be totally blocking the sewer gases. Can you feel a breeze coming from the drain? Use a smoke stick to check for moving air if needed.

[HURDLING]

The trap only has a little bit of water in it. What would you suggest any links to parts etc would be appreciated. Regards

[wine~o]

First thing if the basin is only used occasionally then the water in the trap could be evaporating, solution ? run a tap for 10 seconds every other day.

If it is used regularly then it could be that the loo when flushed creates a syphon in the waste pipe, solution fit an anti-syphon bottle trap.

One other possibility is the waste itself, it should be the slotted type for a basin with integral overflow, possibly a non-slotted waste has been used or the slot is not aligned with the overflow channel.

As a complete aside, soda crystals are not used for getting rid of smells or clearing blocked wastes/traps.

[HURDLING]

Thanks for the advice all, I will try what's recommended. Any further advice will also be welcomed.

[dewaltdisney]

The way a bottle trap works is that there is a central tube that drains from the sink into the bottle and as the water level rises (on draining the sink) the bottle fills up and spills out into the waste pipe. As the basin empties, the water level drops below the waste outlet and a air trap is formed by the water still covering the basin discharge pipe into the bottle therefore stopping smells.

Now my thought are that for some reason the pipe into the bottle might not be long enough to form the air trap so check that out as a possible cause. There might be a suction issue where the water level in the bottle is being sucked out too much on discharge leaving an insufficient water in the bottle to form the seal. Check the run to the drain as it might need a durso valve fitted to cure this.

DWD