Sewage system odours inside can show a completely dry catch, split vent

https://damienprle790.theburnward.com/leak-discovery-101-resolving-hidden-plumbing-issues-in-geelong-houses

Sewer odours inside can show a completely dry trap, broken vent, or partial obstruction; Geelong residential or commercial properties with large trees or older drain lines might need CCTV inspections to find invasions and protect against reoccuring smells