Indoor air quality after a flood: what to actually worry about

After any flooding event, even minor standing water near an outdoor unit or a leak that reached ductwork, the real concern isn’t the water itself — it’s what starts growing in a warm, humid duct system within 24 to 48 hours if it isn’t dried and inspected.

What actually needs inspecting

Any ductwork that took on water directly, insulation that stayed wet more than a day, and the indoor coil and drain pan are the priority. Mold in ductwork gets circulated through every room the system serves — it’s a whole-house problem, not a localized one, which is why it’s worth an actual inspection rather than a guess.

Signs it’s already a problem

A musty smell when the system kicks on, visible discoloration around vents, or anyone in the house developing unexplained respiratory irritation are all signs worth acting on immediately rather than waiting to see if it clears up on its own — it generally doesn’t.

What a real fix looks like

Wet insulation gets replaced, not dried and reused. Affected ductwork gets cleaned or replaced depending on extent. And critically, we find and fix whatever let water reach the system in the first place — otherwise it’s the same problem again next storm season.