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

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

Drain odours inside can suggest a completely dry catch, cracked air vent, or partial clog; Geelong buildings with big trees or older drain lines might need CCTV evaluations to situate intrusions and avoid persisting smells.