How fast does mold grow after a leak?

On wet drywall, carpet pad, and similar materials, visible colonies can start within about 48 hours, sometimes sooner in a warm, humid August house. That is why the first job after a clean-water leak is extraction and drying, not waiting for an adjuster while the pad stays down.

If the water sat for a week, assume you are in remediation territory until a meter and a look say otherwise. Sewage is faster and stricter: porous materials that touched it come out.