Sewer odours inside can show a dry trap, split air vent

https://damienprle790.theburnward.com/crucial-plumbing-maintenance-in-geelong-leak-detection-blocked-drainpipes-and-more

Sewer odours inside can indicate a completely dry trap, split vent, or partial blockage; Geelong residential properties with big trees or older sewer lines might need CCTV examinations to locate invasions and protect against repeating smells.