Sewage system odours inside can show a dry catch, cracked air vent

http://photohistory.oregonstate.edu/works/half/the-importance-of-regular-plumbing-maintenance

Sewage system odours inside can suggest a completely dry catch, cracked vent, or partial obstruction; Geelong homes with huge trees or older sewer lines might require CCTV assessments to find invasions and stop repeating smells.