Toilet smell

Emmia

Vixta1 said:

Emmia said:

Vixta1 said:

Cairnpapple said:

When this happened recently in our bathroom it was a faulty air admittance valve. 

If it was the valve would it not affect the other bathrooms? They are all on the same soil atack

Do you have a wall hung toilet and have you seen any water on the floor? 

We had to get a flexible pipe replaced as vermin had gnawed holes in it, causing small leaks/dripping after flushing... And an associated "aroma" in that bathroom

Not wall hung and no leaks on the floor. Slight almost sewage smell. Not horrific but also not particularly pleasant!

Is there any pipework that might be associated with something else, such as a washing machine near that toilet / that room, rather than the other ones?

WIAWSNB

Vixta1 said:

Cairnpapple said:

When this happened recently in our bathroom it was a faulty air admittance valve. 

If it was the valve would it not affect the other bathrooms? They are all on the same soil atack

Can you confirm this 'soil stack' is a large probably grey or black vertical pipe that runs up the outside wall, and terminates above gutter height with an open top? And the toilet is located close to that wall, and the waste pipe route is clear to see?
If so, you won't have an AAV.
Photo of the underside of the cistern and toilet? 
What's the water level in the pan like? Can you observe it as you flush, and watch what happens at the end - the level should steadily fall to its resting point, but shouldn't suddenly 'dip' as the flow ends, or have a 'glug'.
I know it's hard to trace the source, but have you plonked yer nose in the basin bowl and given it a long slow sniff? Ditto in the bath? And finally in a clean toilet pan? 
When you next catch a whiff, ask someone else to go in holding their breath, and then try these locations one at a time - basin, bath, shower, pan. You do so too - leave the room, acclimatise your nose, hold breath, go back in, approach each item individually, and gently breathe in using yer snozz. And mouth, too. 
Exit, acclimatise, repeat.

WIAWSNB

I guess you could also seal off every item and see if the smell goes away. If so, expose them one at a time.
Basin - plug in, and leave an inch of water over it. Tape up the overflow hole. Bath, ditto. Shower ditto ditto. Toilet pan - I guess clingfilm it!
Actually, before any of that, try sealing the extractor grill. 
Is the smell pretty consistent, and constantly there? If so, it should be much easier to track down by elimination like this.

ic

Another vote for a faulty air admittance valve hidden somewhere in the house.  The rubber seal can get dirt on it preventing it from sealing properly.

Might be in the loft, or boxed in behind a wall.  You might also have mini ones integrated into the u-bend under the sink.

I had one boxed in that was leaking only occassionally - so was hard to identify.  Once I replaced the valve with a decent one (£50 McAlpine one from Screwfix, not any of the £20 cheapies) it solved the problem.