Common Questions
How long does it take for mold to grow after water damage?
Answer
EPA and CDC both use 24 to 48 hours as the window: clean and dry wet materials within that time to prevent mold. After a flood, CDC says that if you couldn't dry your home and its contents within 24–48 hours, you should assume mold is growing.
It's a guideline, not a clock. EPA notes that mold won't always grow after 48 hours, and that it may grow even when materials are dried within 48 hours, so professionals can test if there's doubt.
What the sources say
“If so, and you were not able to dry your home (including furniture and other items) within 24-48 hours, you should assume you have mold growth.”
“Clean and dry wet or damp spots within 48 hours.”
“Even if materials are dried within 48 hours, mold growth may have occurred. Items may be tested by professionals if there is doubt. Note that mold growth will not always occur after 48 hours; this is only a guideline.”