Tile is one of the easiest surfaces in a bathroom to keep clean. Grout is one of the hardest. It is porous cement sitting in the wettest room of the house, so it absorbs soap scum, body oils and minerals, and mould grows in it. The good news: almost any grout can be brought back to its original colour with a $5 paste and twenty minutes of scrubbing, and once it is clean, a coat of sealer keeps it that way for a year. This guide covers what to use on which grout, how to handle shower walls versus floors, the stains that need a stronger approach, and when regrouting is the honest answer.
Key takeaways
- Best all-round method: a paste of baking soda and 3% hydrogen peroxide, 10–15 minutes, then a stiff nylon grout brush. Safe on white and coloured grout.
- Heavy soap scum: warm water with dish soap first, then the paste. Scum has to come off before anything reaches the grout.
- Black mould in grout: peroxide or oxygen bleach; chlorine bleach only on white grout and never on natural stone.
- Never use vinegar or acid cleaners on natural stone (marble, travertine, slate), and go easy with them on cement grout; they slowly dissolve it.
- Seal the grout 24–48 hours after cleaning. Sealed grout wipes clean instead of absorbing everything.
- If grout is crumbling, missing or stays dark after cleaning, regrouting ($200–$600 for a shower) is the fix.
First: what kind of grout and tile do you have?
The right cleaner depends on two things. Get this wrong and you can permanently dull stone or bleach coloured grout.
| Surface | How to tell | Safe cleaners | Avoid |
|---|---|---|---|
| Cement grout, white or light | Slightly rough, absorbs a drop of water in seconds if unsealed | Baking soda + peroxide, oxygen bleach, diluted chlorine bleach, alkaline grout cleaners, steam | Strong acids (they eat cement), wire brushes |
| Cement grout, coloured (grey, beige, charcoal) | Same texture, pigmented | Baking soda + peroxide, oxygen bleach, pH-neutral or alkaline cleaners, steam | Chlorine bleach (fades the colour unevenly), acids |
| Epoxy or urethane grout | Smooth, slightly glossy, water beads on it | Dish soap, alkaline cleaners, a nylon brush. It does not stain; it only needs scum removed. | Abrasive powders, which scratch the surface |
| Ceramic or porcelain tile | Glazed, hard, most bathroom tile | Almost anything, including vinegar and mild acids | Steel wool, scouring powder on glossy tile |
| Natural stone (marble, travertine, limestone, slate) | Veined or layered, feels cool, no uniform glaze | pH-neutral stone cleaner, dish soap and water, peroxide on the grout only | Vinegar, lemon, CLR, any acid, and chlorine bleach. They etch the stone permanently. |
What you need
- Stiff nylon grout brush ($5–$10). The narrow, angled kind. An old toothbrush works for small areas; a drill-mounted brush attachment ($15) saves your wrists on a whole floor.
- Baking soda, 3% hydrogen peroxide, dish soap
- Oxygen bleach powder (OxiClean or a generic percarbonate) for soaks
- Spray bottle, bucket, microfibre cloths, a squeegee
- Rubber gloves; a mask if you use chlorine bleach
- Optional: a handheld steam cleaner ($60–$120), a penetrating grout sealer and a small applicator brush
Step 1: Remove the soap scum first
Most "dirty grout" on shower walls is actually a layer of soap scum sitting on top of the grout. Grout cleaner cannot penetrate it. Start here, every time.
- Run the shower hot for two minutes to warm and soften the surfaces.
- Spray the walls with warm water and a squirt of dish soap (or the vinegar and dish soap mix from our shower door guide on ceramic tile only, never on stone).
- Wait 10 minutes, scrub with a sponge or soft brush, rinse.
- Now look at the grout. Often it is already much lighter.
Step 2: The baking soda and peroxide paste
This is the method that works on 90% of bathrooms, is safe on coloured grout and costs almost nothing.
- Mix about 1/2 cup of baking soda with enough 3% hydrogen peroxide to make a thick paste (roughly 3 tablespoons). Add a teaspoon of dish soap if there is still any greasiness.
- Apply the paste along the grout lines with an old toothbrush or your gloved finger. Work in sections of about one square metre so it does not dry out.
- Wait 10–15 minutes. The peroxide lifts stains and kills mould; the baking soda gives the brush something to scrub with.
- Scrub each grout line with the nylon brush, back and forth along the line rather than across it.
- Rinse with clean water and a cloth, then a second rinse. Baking soda residue leaves a white haze if you skip this.
- Dry with a towel and inspect. Repeat on any lines that are still dark.
Step 3: Stronger options for stains that remain
Oxygen bleach soak (best for floors and coloured grout)
Dissolve oxygen bleach powder in warm water per the package (usually 2–4 tablespoons per litre). Pour or sponge it onto the grout, keep it wet for 30–60 minutes by re-applying, then scrub and rinse. It is colour-safe, fume-free and reaches deeper than the paste. Ideal for a whole bathroom floor.
Chlorine bleach (white grout only)
Mix 1 part bleach to 4 parts water. Apply, wait 10 minutes, scrub, rinse very well. Ventilate and wear a mask. It whitens white grout fast, but it fades coloured grout in patches, corrodes metal fixtures and is not safe on stone. Never combine it with vinegar, ammonia or any other cleaner.
Steam cleaner
A handheld steamer with a nozzle brush blasts scum and mould out of grout with nothing but hot water. It is slow (allow an hour for a shower) but chemical-free and excellent for people with sensitivities. Keep the nozzle moving; sustained steam on one spot can loosen old caulk.
Commercial grout cleaners
Alkaline grout cleaners (the ones sold at tile shops rather than grocery stores) are effective and safe on all grout types. Acidic "grout haze removers" are for new tile installations, not cleaning; they eat cement grout if used regularly. Read the label for the words "alkaline" or "pH neutral."
Grout pen or colourant (the last resort)
If the grout is sound but permanently stained, a grout colourant ($20–$40) paints a new, sealed colour onto clean grout. It looks like new grout for two to five years. It is more work than cleaning and less work than regrouting.
Stain-by-stain guide
| Stain | Cause | Fix |
|---|---|---|
| Even grey darkening | Dirt and soap scum absorbed over years | Paste, then oxygen bleach soak, then seal |
| Black speckles or lines | Mould | Peroxide paste (or bleach on white grout). See our shower mould guide for the ventilation fix. |
| Pink or orange film | Serratia bacteria | Any disinfectant; comes back unless the shower dries between uses |
| White crust on grout and tile | Limescale (hard water) | Diluted vinegar on ceramic tile only, short contact, rinse well. On stone, use a stone-safe descaler. |
| Orange or brown streaks | Iron in well water, or rust from a metal object | Oxalic acid rust remover (Bar Keepers Friend) on ceramic; stone-safe rust remover on stone |
| Yellowing white grout | Body oils, old sealer, hair products | Paste with extra dish soap, then diluted bleach if still yellow |
| White haze on dark tile after cleaning | Baking soda or cleaner residue | Rinse again with clean water and buff dry |
Step 4: Seal the grout
Unsealed cement grout is a sponge. A penetrating (impregnating) sealer fills the pores so water, soap and dirt sit on the surface and wipe off. It is the difference between cleaning grout once a year and once a month.
- Let the grout dry completely after cleaning: 24–48 hours with the fan running and no showers.
- Buy a penetrating sealer labelled for grout and, if you have stone, one that is also stone-safe. Avoid "topical" or membrane sealers in showers; they peel.
- Apply along the grout lines with the small brush or roller applicator (many bottles include one). Wipe any sealer off the tile face within five minutes; on glazed tile it does nothing and can leave a haze.
- Wait the cure time on the label (usually 1–2 hours between coats, 24 hours before water). Apply a second coat.
- Test with a few drops of water. If they bead, it is sealed. If they soak in, add a coat.
- Re-seal shower walls yearly and floors every 1–2 years. Epoxy grout never needs sealing.
Cleaning the tile itself
- Glazed ceramic and porcelain: dish soap and warm water for weekly cleaning; the vinegar and dish soap spray for scum; a microfibre cloth to dry. That is genuinely all it needs.
- Matte or textured porcelain floors: these hold dirt in the texture. An alkaline tile cleaner and a deck brush, then a thorough rinse. Avoid oil-based "shine" products, which build up and make the floor slippery.
- Glass mosaic: vinegar-water spray and a soft cloth; never abrasives.
- Natural stone: pH-neutral stone cleaner only. Re-seal the stone itself yearly. Etch marks from acid can only be removed by professional honing.
- Grout haze on new tile: a cement film left after installation. Use a haze remover from the tile shop once, then never again.
Keeping it clean
- Squeegee the walls after each shower and run the fan for 20–30 minutes. Dry grout does not grow mould and does not absorb scum.
- Weekly: spray a daily shower cleaner or diluted dish soap and rinse. No scrubbing.
- Monthly: a five-minute pass with the peroxide paste on the lines that get the most water (the floor of the shower and the bottom row of wall tile).
- Yearly: deep clean and re-seal.
- Switch to liquid body wash. Bar soap is the main ingredient in soap scum.
- If you are on well water, a softener stops the limescale that turns grout white and rough.
When cleaning is not enough: regrout or retile
Grout that crumbles when you scrub it, has gaps you can fit a fingernail into, or stays dark after an oxygen bleach soak has reached the end of its life. Water is getting behind the tile through those gaps, and that is how walls rot.
- Regrouting (removing the top few millimetres of old grout and applying new) costs $200–$600 for a typical shower in Ontario, or a weekend and $50 in materials if you do it yourself with an oscillating tool and a grout removal blade. Use epoxy grout this time and you will never seal or bleach it again.
- Retiling is the answer when tiles are loose, sound hollow or the wall behind is soft. A full shower retile with proper waterproofing runs $3,000–$8,000, and it is the moment to rethink the whole shower. Our walk-in shower planning guide and bathroom renovation cost guide cover what to expect.
Retiling the shower? Finish it properly.
Thermostatic and pressure-balanced shower systems, rain heads and hand showers from Kodaen and Lauretta. Delivered across Ontario, free on orders over $600.
Frequently asked questions
What is the best homemade grout cleaner?
A paste of baking soda and 3% hydrogen peroxide. It lifts stains, kills mould, is safe on coloured grout, and costs a few cents. Leave it 10–15 minutes and scrub with a nylon grout brush.
Can I use vinegar to clean grout?
Occasionally on ceramic tile with cement grout, diluted and rinsed quickly, it removes limescale. Regular use slowly dissolves cement grout, and vinegar must never touch natural stone. Peroxide or oxygen bleach is the better everyday choice.
Does bleach damage grout?
Diluted chlorine bleach is fine on white cement grout in moderation. It fades coloured grout unevenly, weakens grout with repeated use, and etches stone. Oxygen bleach is safer for everything except the most stubborn white-grout stains.
Why does my grout get dirty so fast?
It is unsealed, so it absorbs soap scum and water like a sponge. Clean it thoroughly, let it dry for two days, and apply a penetrating sealer. Sealed grout wipes clean.
How do I clean grout without scrubbing?
An oxygen bleach soak kept wet for an hour does most of the work, and a steam cleaner does the rest. A drill-mounted brush removes the effort from what scrubbing remains.
Is Magic Eraser safe on grout?
Yes on cement grout and glazed tile. It is a fine abrasive, so avoid it on epoxy grout and polished stone.
