You see a gray or black patch in the shower, on a windowsill, or along a wall, and the first question is: is this mildew, or is it mold? They’re related, but they’re not the same problem, and one is a lot more serious than the other.
The Short Answer
Mildew is a type of mold that grows flat on the surface of damp things like tile, grout, shower curtains and windowsills. It’s usually easy to wipe off. Mold, in the everyday sense, often grows deeper into materials like drywall, wood and carpet, and can mean there’s a moisture problem behind the surface.
How to Tell Them Apart
| Mildew | Mold | |
|---|---|---|
| Color | White, gray, or light yellow; can darken over time | Black, green, blue, or brown; often in patches |
| Texture | Flat and powdery | Fuzzy, slimy, or raised |
| Where it grows | On the surface: tile, grout, glass, fabric | Into materials: drywall, wood, ceilings, carpet |
| Cleanup | Usually wipes away | Often needs the material removed |
| What it signals | Surface humidity | Possible leak or ongoing moisture |
A Simple At-Home Test
Put on gloves and dab the spot with a cotton swab dipped in a little diluted bleach. If it lightens within a couple of minutes and wipes away easily, it’s likely mildew. If it stays dark, keeps coming back, or seems to be inside the material, treat it as mold. This is a rough check, not a lab test.
How to Handle Mildew
- Scrub with a household cleaner or soap and water and dry the area well.
- Run the bathroom fan during and after showers.
- Keep indoor humidity between 30% and 50%.
- Wash or replace shower curtains and bath mats regularly.
When It’s Probably Mold, Not Mildew
- It’s on drywall, a ceiling, baseboards, or furniture, not just tile or glass
- The material underneath is soft, stained, or warped
- There’s a musty smell even when you can’t see anything
- It came back after you cleaned it
- There’s been a recent leak, flood, or AC problem
Any of these usually means there’s moisture behind the surface. In Florida’s humidity, that can spread quickly. See our guides on how to identify black mold and finding hidden mold in your house.
A professional mold inspection tells you what you’re dealing with and where the moisture is coming from. If it’s mold, licensed mold remediation removes it and fixes the cause so it doesn’t come back.
Still Not Sure? Request a Free Visual Inspection
FL Cleanup offers a free visual inspection with moisture readings and an infrared (thermal) camera across South Florida. We answer 24/7, and hablamos español. Call 877-224-2532 or request a free visual inspection online.
About the author: James Rice-Peña is the owner of FL Cleanup and a Florida-licensed Mold Assessor (MRSA4035) and Mold Remediator (MRSR4158). He has worked in property restoration in South Florida since 2012, and FL Cleanup has earned 200+ five-star Google reviews.
