Sewerage odors into bathroom.

[Andyoc]

Hi all I'm hoping I can get some help as we are at a brick wall with this.

my partner rents a end terrace which is a hair salon, it has a down stairs toilet in the back which occasionally smells VERY BAD! Like raw sewerage (not very nice in a hair salon).

it comes and goes which is odd, it is worse in the winter and when it rains heavily.

we have had the water board out who have put cameras up all the pipes ect and they have said no pipes under ground are busted.

the land lord has said it has been like it for years and he could never get to the bottom of it.

the exterior stack is cracked.... Could this really be the cause? It's the only thing I can see is wrong.

has anyone else ever had this issue? Can any one please offer some advise on what to look for to get to the bottom of what this is?

we have had a plumber out who 'guessed' it could be a cracked waste pipe under / from the loo to the sewer..... £500 charge to rectify... Expensive guess IMO.

SOMEONE PLEASE HELP

 

[JCplumb]

The cracked stack will release odours, that needs sorting for a good bit less than £500.
The smell 'could' be coming in through a vent brick and getting into the wall cavity and under the floor, if there are wooden floors the smell will come up through them.
My mum had this issue for years where she could smell the drain (that is under her kitchen window) in her front room. It was because the kitchen has a solid floor and the front room has a wooden floor, so that's where it was coming up.