How to Remove Mold and Mildew From Shower Grout and Caulk
Black or pink spots in the shower are usually mildew, a surface mold that loves warm, damp places. Most of it comes off with simple products. Stains inside caulk sometimes mean the caulk needs replacing.
Quick answer
- Spray grout with 3% hydrogen peroxide, wait 10 to 15 minutes, and scrub with a stiff brush.
- For stains, scrub with a paste of baking soda and water.
- Rinse, then dry the area and run the fan.
- Replace caulk if the black is under the surface.
In this guide
Method 1: Hydrogen peroxide (gentle)
- Spray 3% hydrogen peroxide directly on moldy grout.
- Wait 10 to 15 minutes.
- Scrub with a grout brush or old toothbrush.
- Rinse and dry.
Method 2: Baking soda paste (for stains)
Mix baking soda with a little water into a paste. Spread it on the grout, spritz it with peroxide or water, wait 10 minutes, scrub, and rinse.
Method 3: Diluted bleach (white grout only)
For stubborn black spots on white grout:
- Open a window and turn on the fan. Wear gloves.
- Mix 1 part bleach with about 10 parts water.
- Apply with a brush, wait 10 minutes, scrub, and rinse thoroughly.
Never mix bleach with vinegar, ammonia, or other cleaners. Rinse away any earlier products before using bleach. Bleach can discolor colored grout.
Moldy caulk
Wipe on the peroxide or diluted bleach and leave a soaked paper towel on the caulk for a few hours. If the black is still there, the mold is under the surface. Cut out the old caulk, let the area dry completely, and apply new mildew-resistant silicone caulk.
Keep mold from coming back
- Run the bathroom fan during showers and for 20 to 30 minutes after.
- Squeegee walls and doors.
- Wash shower curtains and liners monthly.
- Seal grout every year or two.
- Fix leaks and keep the room’s humidity down.
When to call a pro: large areas of mold, mold on drywall or ceilings, or a musty smell you can’t find the source of. These can signal a hidden leak.
FAQ
Does vinegar kill mold? White vinegar works on many common household molds. Use it instead of bleach, never together.
Always test a cleaner on a hidden spot first and follow the care label. Never mix bleach with ammonia, vinegar, or other cleaners. Ventilate the room and wear gloves when using strong products.