Intermittent bad smell

4 Jul 2021
Reaction score
United Kingdom
Hi all

We've been experiencing an intermittent smell from our downstairs toilet for the last few months. We've tried replacing the pan connector and have had a CCTV inspection on the drain, but the problem persists. Last week I removed the toilet again and disconnected the sink trap. Both have been capped but we're still getting the smell.

The pipework is boxed in, but I've cut a hole to inspect. The pipes are covered in dust and there are no visible leaks.

The soil stack also services our bathroom on the first floor. It's boxed in here too, but there is a large gap behind our vanity unit. Despite this, we've never experienced a smell in this room. The stack isn't vented externally, so, I assume it's capped internally.

Air is forced through the pan connector when we flush the upstairs toilet, but I can't feel any air coming through the inspection holes. I can feel a fairly strong draught, but it doesn't seem to be carrying a smell, or at least not today. The soil pipe is insulated, but it looks like the insulation is missing at the bottom.

Could the smell be drawn in from the outside? We've tried to trace the smell outside before but it seemed to be isolated to this room.

Thanks in advance for your help.


  • IMG_20221117_123948.jpg
    191.7 KB · Views: 39
  • IMG_20221121_182340.jpg
    203.1 KB · Views: 46
  • 16690617388381580893329430475217.jpg
    332.4 KB · Views: 41
  • 16690617633423749008527264314540.jpg
    263 KB · Views: 38
  • 16690617836395504815977341858687.jpg
    458.1 KB · Views: 45
Sponsored Links
31 years ago, my girlfriend had exactly the same symptoms in a downstairs airing cupboard that contained the stack from the bathroom next to it. A horrible smell would come and go, it suddenly started happening and just in that space.

Being eager to impress, I tried several times to find the cause, but to no avail. Eventually my GF became Mrs Stem and left the property she shared with a friend to live with me. Several months later we learned from her friend that during a period of 'stench' a rat was seen scuttling across the airing cupboard shelf, and a rodent catcher had been subsequently engaged. End of the problem. Droppings were found behind the hot water cylinder, and some old curtains in a bag had been chewed.

It was never confirmed how they were getting in, there wasn't anywhere obvious, although the rat catcher suspected they came from the adjoining house next door somehow, but the neighbours weren't noticing a smell.

Hopefully, this may not be your issue, but it's something you may want to consider during your investigations.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links