Mold vs Mildew: How to Tell the Difference

“Mildew” is what most homeowners call mold when they don’t want to admit it might be a real problem. Technically, mildew is a type of mold — but the distinction matters because they call for different responses.

Mildew: Surface, Powdery, Cleanable

Mildew lives on the surface of materials and looks powdery — usually white, gray, or yellow. It’s commonly found on bathroom tiles, shower curtains, plants, and damp fabric. You can scrub it off with a vinegar solution or commercial cleaner, and as long as you fix the moisture source, it doesn’t come back fast.

Mold: Penetrating, Slimy or Fuzzy, Removal-Required

Mold goes into the material it grows on — drywall paper, wood fibers, carpet padding. It looks fuzzy or slimy and comes in colors ranging from green to black to pink. Cleaning the surface doesn’t get the colony underneath, which means it grows back within weeks. Real mold requires removal of the affected material.

Quick Field Test

Spray a bit of household bleach on the patch. Wait 1-2 minutes. If the patch lightens significantly, it’s probably mildew (surface). If it stays dark, it’s probably mold (penetrating).

This test is informational only — don’t use it as a basis for not calling a professional if you have visible growth larger than a dinner plate.