How to Remove Mold From Grout — and When It's Beyond DIY
26.08.2026
To remove mold from grout, scrub the grout lines with a stiff nylon brush and a paste of baking soda and water, rinse, then apply a grout-safe mildew stain remover, let it sit per the label, scrub again, and rinse. Dry the area well with a towel and run your bathroom fan to keep moisture down. Repeat for stubborn stains.
What you'll need
- Stiff nylon grout brush or an old toothbrush
- Baking soda and a small bowl
- Spray bottle
- White vinegar (for loosening soap scum, not as a disinfectant)
- An EPA-registered mildew stain remover labeled for tile and grout (read the directions)
- Chemical-resistant gloves and a mask or respirator
- Microfiber cloths and an old towel for drying
- A bucket of clean water for rinsing
Step by step
- Ventilate first. In a NYC bathroom with a non-opening window, turn on the exhaust fan and crack the door. Never mix vinegar with a chlorine-based product — the fumes are hazardous.
- Clear the surface. Wipe away loose soap scum and grime so the cleaner reaches the grout, not the film on top of it.
- Mix a baking soda paste (about three parts baking soda to one part water) and spread it along the stained grout lines.
- Scrub with a stiff nylon brush, working in short back-and-forth strokes along the grout, not across the tile face.
- Rinse with clean water and check what's left. Surface grime often lifts here; deeper staining needs a targeted product.
- Apply an EPA-registered mildew stain remover made for grout. Follow the label's dwell time exactly — don't guess, and don't leave it on longer than directed.
- Scrub again, rinse thoroughly, and wipe the grout dry with a towel.
- Dry the whole area and leave the fan running for 20-30 minutes. Grout that dries fast stains far less often.
What NOT to do
Don't reach for a wire brush or a scouring pad on grout. Metal bristles gouge the grout and scratch glazed tile, and the grooves you leave trap more moisture. Skip aggressive acids on natural stone tile like marble or travertine — vinegar and many bathroom cleaners etch stone, leaving a dull, rough patch that no amount of scrubbing fixes. Don't mix products: bleach-based and ammonia-based or acidic cleaners together release dangerous gas, a real risk in a small, poorly ventilated apartment bathroom. And don't paint over stained grout with a "grout pen" while it's still damp underneath — you're just sealing moisture in.
When to call a pro
DIY handles surface staining on the grout between wall and floor tile. It stops working when the discoloration keeps coming back within days, when it's spreading behind the tile or up the drywall, or when the grout is cracked and crumbling — that points to a moisture problem inside the wall that scrubbing can't reach, and in a rental it's your landlord's job to address the leak. If you just want the bathroom deep-cleaned and the grout brought back before an inspection or move-out, book apartment cleaning with CleanWhale and let a team handle the scrubbing and drying.
FAQ
Does vinegar remove mold from grout?
Vinegar can help loosen soap scum and lighten some staining, but it's an acid, not a disinfectant, and it will etch natural stone. Use it only on ceramic or porcelain tile, and rely on a product labeled for the job when you need more than surface cleaning.
Why does the mold keep coming back in the same grout line?
Grout is porous and holds water. In a NYC bathroom without a window, staining returns when the area never fully dries. Run the exhaust fan during and after showers, squeegee the walls, and wipe the grout dry. If it still returns fast, there may be moisture inside the wall.
Can I use bleach on colored grout?
Bleach-based products can lighten or discolor tinted grout and dull nearby finishes. Test any cleaner on a hidden spot first, and follow the label. Never combine it with vinegar or ammonia.
Is it safe to seal grout after cleaning?
Once the grout is clean and fully dry, a penetrating grout sealer makes it less porous and easier to keep clean. Make sure it's completely dry first — sealing over damp grout traps moisture. Check your lease before making changes in a rental.
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