Indoor air and moisture

Why does my basement smell musty?

A musty odour usually indicates persistent moisture supporting microbial growth, damp materials, or a drainage/ventilation problem.

Urgency: moderate

What this means

Find and control moisture rather than masking the smell with fragrance or ozone.

Use a hygrometer
check around foundation walls, plumbing, floor drains, stored cardboard, and dehumidifier drainage.

Use professional assessment for sewage odour, large wet areas, repeated flooding, hidden growth, or health symptoms.

Contact the matched licensed or qualified trade if safe checks do not resolve the issue.

This answer combines HomeSOS's structured triage with safety boundaries supported by a public source. It does not replace inspection.