stink - but no obvious source!

[marmic]

morning all,

 

We have a stink emanating from somewhere around trap under sink - but no water leak.  1  1/2" plastic waste.  Could the trap be 'faulty' somehow?  It's not dry/blocked etc etc - (no smell from sink).  There's also an elbow after trap.  Both removed, cleaned, reinstalled - but still stinks.  not making any sense -    new fittings maybe?

 

any bright ideas please?  very frustrating!

[Russell griffiths]

Got a picture. 

[MikeSharp01]

Sounds like your system is open to the main sewer, have you got a dry trap somewhere - washing machine for instance or maybe an air admittance valve (AAV) is stuck and your loo flushes are sucking a trap dry.

[FarmerN]

We have a problem with the dishwasher connection but that’s above the trap and smells from the sink and you say “ (no smell from sink)”.

Is it a drain/ sewer smell?

No chance of a dead mouse under/ behind units?

[marmic]

wish it was a dry trap - would probably be an easy fix just adding another one in line - or a deeper one.  Kitchen traps fine, shower trap fine (and on separate run as these can get vacuumed out easier if combined!)

 

and no dead mice 😁  (or a gone off bag of carrots - had that many years ago in another house, found it eventually disappeared behind a cupboard without a proper back. Believe me that reeked!)

 

yes very much drain smell (from STP).  Rapidly concluding to try new/different trap and new elbow.  Thinking maybe gas escaping at top of a joint where it won't drip????  but no obvious damage  / cracks etc.  So so weird............

 

thankfully this is in plant/utility room where we can shut door - and decent mvhr extraction!  Also good we've intentionally left all pipes etc either exposed or accessible

 

AAV internally and also on SVP externally.  STP vented with carbon filter on effluent pump pod (gravity fed from STP - kept it separate for ease of replacing pump if it ever packs up - works hard pumping c. 240m, and max 2m rise albeit little head. obviously non return)

 

 

 

[-rick-]

Where does the lower pipe (below the floor of the cabinet) go? Any joins in it? Just wondering if the smell is travelling a bit and leading you off track? Smell could migrate into the cupboard and accumulate through those cut outs while the mhvr clears the rest of the room.

[Nickfromwales]

Change this bend from a push fit to a compression. 
 

 

See if that improves it. The seals on those are crap, so the water may be at the bottom of the pipe when leaving, and a gap in the seal may be at the top, and you’d get no water leaking.
 

I’d start there.
 

Also, push a cloth into the hole behind it, to rule out if the smell is coming through the hole and not from the pipe under there.