Prep first
Before you start
- Fix the water source first, since moisture is what lets mold return.
- Wear gloves, goggles without vents and an N-95 respirator so you don't breathe in or touch spores.
- Brush loose mold off outdoors if you can, so spores don't scatter through the house.
- Dry the area within 24 to 48 hours, because wet areas dried in that window usually won't grow mold.
Mold on shower grout usually means water keeps lingering in the lines. Whether the stain can be fully cleared depends on the grout itself: cement-based grout can hold a stain for good, while epoxy grout can always be brought back to its original shade. Fresh growth lifts more easily than an older mark that has bonded into the grout, and deep marks on cement grout may need a professional.
Cleaning mildew from shower grout goes best with the washing soda wash, then a baking soda scrub, and let the wash sit before you scrub. Washing soda and baking soda can lift fresh growth, but black mold in tile grout usually needs more than that. If the dark lines still show after a couple of rounds, stop and call a professional.
Before you start
What grout can take
Safe to use4
- Water
- Hot water
- Enzyme cleaners
- Heat, once the stain is out
Use with care5
- Soaking
- Chlorine bleach
- Solvents (alcohol, spot removers)
- Acids (vinegar, lemon)
- Scrubbing and abrasives
6 items
What you'll need
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- White nylon pad or nylon brushThe recommended tools for grout, and the ones the steps assume. (opens Amazon)
- Old toothbrushGets down into the grout line where a pad can't reach.
- Washing sodaThe base of the main wash, at 1/4 cup per gallon of warm water. (opens Amazon)
- Baking sodaA gentle cleanser for the scrub, and the base of the bleach paste. (opens Amazon)
- Chlorine bleachOnly for a dark stain left after the rest of the job. (opens Amazon)
- Clean water and a spongeFor rinsing each section as you go. (opens Amazon)
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6 steps
Step by step
Step 1 of 6
Wet and scrub the grout
Wet the grout lines with warm water first. Then scrub them with a white nylon pad or an old toothbrush, working one small section at a time.
Step 2 of 6
Wash with the washing soda solution
Mix 1/4 cup washing soda into 1 gallon of warm water and wash the grout with it, starting at the top of the wall and working down. Keep the solution moving across each line so the whole section gets covered before you move on.
Careful. Don't let the washing soda solution dry on the grout.
Step 3 of 6
Rinse every line thoroughly
Rinse with clean water and go over each line until the grout no longer feels slick. Wipe the tile faces as you go so the rinse water doesn't leave streaks.
Careful. Leftover cleaner leaves a sticky soap film if it isn't rinsed away.
Step 4 of 6
Scrub with the baking soda
Sprinkle baking soda onto a damp sponge and scrub the stained lines in small circles. Rinse again with clean water once the marks start to lift or the scrub stops picking anything up.
Step 5 of 624 to 48 hours
Dry the grout completely
Dry the grout with a clean towel, then let the air move across it until every line is fully dry. Check the lines only once they're dry, since damp grout can hide a stain that's still there.
Step 6 of 6
Bleach only what remains
If a dark stain is still on the dry grout, mix chlorine bleach with baking soda into a paste and scrub it on with a small brush. Rinse it out completely, then let the grout dry again.
Careful. Never mix bleach with ammonia or an ammonia-based cleaner, because the mix forms toxic gas.
If you'd rather buy than mix
Best products for mold on grout
If a stain lingers after the wash, reach for a commercial mildew remover made for grout. Follow the directions on its container, and patch-test it on an inconspicuous area first.
MOLD ARMOR Rapid Clean Remediation
How we picked these: each product is made for this type of stain, its maker doesn't warn against using it on grout, and its directions fit the steps above.
Finished the steps? How does it look?
Nice work. Let it dry completely and check it again in good light. Here is what done looks like:
How to tell it's really gone →A faint mark usually needs one more round, not a stronger product.
See what to do for what you're seeing →Heavy buildup usually takes more than one round.
Heavy or long-standing buildup →When to call a professional →How to tell it's working
The grout should look even in color, with no gray haze, and the lines should feel smooth rather than slick. If a dark patch still shows once everything is dry, it's a stain for the set-in options below.
What changes for yours
Adjust for your grout
Tile or bathroom grout
The same steps work on tile and bathroom grout. The washing soda wash is the right choice here, since strong acid solutions can leave grout powdery and dull glazed tile.
For the tile itself, see our Tile guide, since the surface needs its own care. Check the wall in good light after each rinse so you catch any dull patch early.
Cleaning mildew from shower grout
Mildew on shower grout usually responds to the washing soda wash and rinse on its own. Keep the wash mild and let the grout dry fully afterward, since moisture is what brings it back.
If the grout still looks dingy once it's dry, the baking soda scrub is the next move before you consider bleach. Check the lines in good light so you can tell a faint mark from a clean surface.
Mildew stains
A stain that has been there a while needs patience rather than stronger cleaners. Work through the steps in order once before you repeat any of them, so you can see which part is doing the work.
Repeat only the scrub that's still lifting color, and rinse fully between each pass. If a stain stays after drying, move on to the set-in options.
Black mold on grout
Black marks in grout often sit deeper than surface mildew, so expect to need the bleach step at the end. Work through the washing soda wash, rinse and baking soda scrub first, so the bleach only has to deal with what's left.
Check the result only after the grout is fully dry, since damp grout can hide a stain that's still there. If black marks remain, the set-in options cover the stronger treatments.
Heavy or long-standing buildup
Old red or orange marks have had longer to soak into the grout, so the steps above may only lighten them. Stains that become part of cement grout are the hardest to clear, while epoxy grout can always be cleaned back to its original color.
For deep stains on cement grout, use an alkaline grout cleaner and let it dwell for up to 10 minutes. Then scrub with a nylon pad for 60 seconds and rinse it out completely before the grout dries.
Pressurized steam can lift stains that don't respond to regular cleaners, so it's the next option before you decide anything else. Once the grout is dry, check the result, since mold can fill crevices and may be difficult or impossible to remove completely. If it's still there, replacing the grout may be the only option.
Vinegar, baking soda, peroxide and more
Do home remedies work on mold on grout?
Plenty of remedies circulate for mold, but many were written for fabric or stone. Here's how each one fits shower grout, and which ones stay out because cement grout can't take them.
Works2Helps1Skip2Avoid2
Chemical safety
Never mix these
Some products in this guide react dangerously with each other. Use them one at a time and rinse with water in between.
Chlorine bleach + Hydrogen peroxide (3%)
Washington State's health department says bleach reacts with hydrogen peroxide, and Clorox says not to mix bleach with other household chemicals.
Chlorine bleach + Washing Soda
Clorox says not to mix bleach with other household chemicals, and no maker statement allowing bleach with washing soda was found.
If they mix by accident: Don't use the mixture; ventilate the room and avoid breathing fumes or touching it; call Poison Control at 1-800-222-1222 for disposal advice or if anyone feels unwell.
What makes it worse
Mistakes to avoid
Don't use vinegar or lemon on cement grout.
Both are acids, and they etch cement-based grout. Never combine either one with chlorine bleach.
Don't use oil- or wax-based cleaners.
They leave a film in the grout. The washing soda and baking soda steps are the cleaners to stick with.
Don't use strong cleaners for routine care.
Strong alkaline, abrasive or ammonia-based cleaners can damage grout and greatly reduce its stain repellency. Keep the routine wash mild, and save stronger options for a stain that won't lift.
Don't rely on bleach for routine cleaning.
Chlorine bleach isn't recommended as a routine practice for mold, so it belongs only at the end of the job. If you do use it, keep the room well ventilated and exhaust the air outdoors.
Don't paint or caulk over mold.
Clean and dry the surface first, because paint over mold is likely to peel. Covering the stain hides it without fixing the cause.
Troubleshooting
If the stain is still there
Pick what you're seeing:
A sticky film remains on the grout.
Cleaner residue was left behind. Rinse again with clean water and remove the rinse water before it dries.
Dark stains won't lift from cement grout.
Stains can become part of cement grout. Try steam, then contact the grout maker's technical support for options.
When to call a professional
Call a professional if the mold covers more than about 10 square feet or came from sewage or contaminated water, since those jobs need proper remediation. Acid cleaning on deeply set grout stains also belongs with a pro, because it needs extreme care.
Questions
What's the best way to clean moldy shower grout?
Start with the washing soda solution of 1/4 cup in 1 gallon of warm water, scrub with a nylon pad or old toothbrush, then rinse thoroughly. Dry the grout completely and check it, and use the baking soda scrub only on what's left.
Can I clean mold off grout without bleach?
Yes. The washing soda wash and the baking soda scrub both work without bleach. Bleach only enters at the end, for a stain the others leave behind.
Does chlorine bleach remove mold from shower grout?
It can, but only for a dark stain that's still there after the rest of the job. It goes on last, once everything has been rinsed out and the grout is dry.
Which mold remover should I buy for grout?
Start with the washing soda and baking soda from the steps. If you still need more, choose a mildew stain remover made for grout and test it on a hidden spot first.
How do I remove red or orange mold from old grout?
Run through the steps first, then the set-in options. If the color stays after that, the grout may be too damaged to clean, and replacing it is the realistic fix.
Why does mold keep coming back on shower grout?
Mold needs moisture, so it returns when the grout stays wet after showers. Run the fan, wipe the walls down after use, and make sure the area dries within a day or two.
Methods, care labels and related guides
Good to know
Mold on other materials
Other stains on grout
Start from the bigger picture
How we know this
Every method, amount and warning here comes from university extension services, industry bodies and product makers. We read them, check every step for unsafe combinations and changed amounts, and write it up so you can follow it.