How fast can mold grow after water damage?
The EPA says to dry water-damaged areas and items within 24 to 48 hours to prevent mold growth (EPA). The EPA's remediation guide adds that even if materials are dried within 48 hours, mold may have grown, and that mold will not always grow after 48 hours (EPA).
What should be dried first?
Porous materials that can't easily be cleaned: carpet and pad, drywall, insulation and upholstered furniture. The EPA says ceiling tiles and wet insulation should be discarded and replaced (EPA).
Does Atlanta's humidity make it worse?
High humidity slows drying. The EPA recommends keeping indoor humidity below 60%, ideally 30 to 50% (EPA). Keeping the AC running and using dehumidifiers helps, as long as the system is not contaminated.
What if the house was closed up?
The CDC says that if a flooded home has been closed up for several days, assume it has mold (CDC).
Common questions
Can mold grow in 24 hours?
The EPA's guidance is to dry within 24 to 48 hours because mold can begin in that window.
Will mold always grow after a leak?
No. The EPA notes mold does not always grow after 48 hours, but the risk rises the longer things stay wet.
How do I know if mold has started?
Look for spots, discoloration and a musty smell. Hidden areas like the back of drywall need to be opened or checked.
Related guides
Sources
- EPA: A Brief Guide to Mold, Moisture and Your Home
- EPA: Mold Remediation in Schools and Commercial Buildings, Table 1
- CDC: reentering your flooded home
Last reviewed November 13, 2026. This guide is general information, not legal, insurance or medical advice.