Sewage system odours inside can show a dry trap, cracked vent

https://canvas.pasadena.edu/eportfolios/4924~6653/home/common-plumbing-leaks-that-you-may-experience-in-your-home

Sewer odours inside can suggest a dry trap, split vent, or partial clog; Geelong buildings with large trees or older drain lines might need CCTV assessments to find intrusions and avoid reoccuring scents.