Sewage odor

Strong wastewater or sewer-gas odor associated with traps, drains, vents or leaks.

First distinction

Note where the odor is strongest, whether it appears with rain, wind, heating, plumbing or ventilation, and whether closing a door changes it.

Do not mask the pattern

Fragrance can make the pathway harder to identify. Record timing before cleaning or moving stored material.

Next useful step

Compare nearby materials and systems, then use one controlled isolation check at a time.