Sorry the open hole is behind my kitchen wall and the overflow pipe is just above the hole small white pipe and the circle above is another flat showing there area has been bricked up with overflow pipe sticking out this picture shows the other flats bricked up in same area mine has open hole if...
I have had multiple contractors round to fix drains stack pipes and yesterday found condensate pipe under sink had small crack and they thought this was causing the smell. Since then smell is now worse under sink and behind cupboard were the internal stack is . I have only recently noticed the...