How soon does mold grow after a water leak?
It can start within two days. The EPA says that if wet materials are dried within 24 to 48 hours, mold usually will not grow. The CDC says that if a home was flooded and you could not completely dry it, including furniture, within 24 to 48 hours, you probably have mold, even in places you cannot see.
On this page
The clock starts when the material gets wet, not when you first notice a smell. Two federal pages put the same window on it.
What the EPA says
The EPA mold guide says it is important to dry water-damaged areas and items within 24 to 48 hours to prevent mold growth. In another line on the same page, it says that if wet or damp materials are dried 24 to 48 hours after a leak or spill, in most cases mold will not grow. The guide also asks you to keep indoor humidity below 60 percent, and ideally between 30 and 50 percent, once the room is dry.
Spores are already in house dust. They need moisture to grow.
What the CDC says after a flood
The CDC is stricter once outdoor water has been in the house. Its respiratory cleanup page says that if the home was flooded and you could not completely dry it out, including furniture and rugs, within 24 to 48 hours, you probably have mold. The same page says mold can hide under cabinets, carpet, cushions, or inside walls even when you cannot see or smell it.
What that means tonight
If the leak is still new and the water is clean supply water, moving air and pulling water now is the job. What to do when water is in the house is the order. If the house sat wet through a weekend, plan for hidden mold and for materials that cannot be saved.
If outdoor flood water came in, read the CDC flood pages as well. The Cedar Rapids page covers the floodplain permit there.
Sources
Who wrote and checked this page
- Written by
- Soaked SOS editorial staff. Who runs this site
- Facts checked
- , by the Soaked SOS editorial staff, against the sources listed on this page.
- Licensed professional
- None. No licensed restoration contractor or industrial hygienist has checked this page.
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