Grout is the weak point of any tiled surface. Porous, textured, and recessed — it collects everything that misses the tile. Mildew settles in damp bathroom grout within days. Soap scum glazes kitchen backsplash lines. Floor grout collects dirt and looks gray even after mopping. The fix isn't a specialty product; it's the right abrasive, a stiff brush, and a few minutes of actual scrubbing.
What changed in 2026
- Oxygen bleach (sodium percarbonate) products became the mainstream recommendation over chlorine bleach for home use — effective on stains without fume risk or color damage.
- Electric grout brushes and oscillating tool grout attachments dropped in price; an attachment for a $20 oscillating tool now makes floor grout a 15-minute job.
- Grout sealers improved — penetrating silicone-based sealers last 3–5 years on floor grout with a single coat.
The grout-cleaning ladder
| Level |
Stain type |
Product |
Time |
| Light |
Surface dirt, soap film |
Warm water + dish soap |
5 min |
| Moderate |
Body oil, light mildew |
Baking soda paste |
15 min |
| Heavy |
Deep mildew, grease |
Oxygen bleach solution |
30 min |
| Severe |
Permanent staining |
Commercial grout cleaner or regrout |
Varies |
Start at the lowest level that matches your stains. Escalating to harsh chemicals for a light-soap-film problem damages grout over time.
How to clean grout step by step
Method 1: Baking soda paste (moderate stains)
- Mix baking soda with enough water to form a thick paste.
- Apply the paste to the grout lines with a finger, old toothbrush, or spatula.
- Let it sit for 5–10 minutes.
- Scrub firmly along the grout line with a stiff-bristled grout brush or electric toothbrush.
- Rinse with warm water and dry the surface.
Optional: spray white vinegar on the paste before scrubbing — the fizz helps lift stains. Rinse thoroughly; vinegar can weaken grout with prolonged contact.
Method 2: Oxygen bleach (heavy stains, mildew)
- Mix oxygen bleach powder with hot water per product instructions (typically 1 scoop per 1–2 cups water).
- Apply generously to the grout lines. Allow to soak for 15–30 minutes — the longer, the better for mildew.
- Scrub with a grout brush.
- Rinse thoroughly with clean water.
This method is safe on most colored grout. Ventilate the room; oxygen bleach releases oxygen gas (not toxic, but ventilation is good practice).
Method 3: Floor grout (large area)
- Sweep and vacuum first to remove loose dirt.
- Apply diluted oxygen bleach solution across the area.
- Let soak 20 minutes.
- Use an oscillating tool with a grout brush attachment, or a heavy-bristle deck brush.
- Mop with clean water twice to rinse.
How to seal grout
Sealing after cleaning keeps grout clean longer. Use a penetrating silicone-based sealer:
- Ensure grout is completely dry (24–48 hours after deep cleaning).
- Apply sealer with a small applicator bottle or brush directly to the grout line.
- Wipe excess off tiles immediately before it dries.
- Allow to cure per product instructions (usually 24–72 hours before water exposure).
Floor grout: reseal every 2–3 years. Shower grout: reseal every 1–2 years.
Common mistakes
Not scrubbing enough. No product substitutes for mechanical action on grout. The bristle does the work; the product helps. Scrub firmly.
Using chlorine bleach on colored grout. Chlorine bleach strips color pigment from sanded and unsanded colored grout. Use oxygen bleach instead.
Skipping the seal. Cleaned but unsealed grout restains in weeks in a shower environment. Sealing is not optional for lasting results.
Mopping grout without pre-scrubbing. A mop pushes dirty water into grout; it doesn't clean it. Scrub first, then mop with clean water.
Leaving vinegar on natural stone tiles. Vinegar and acidic cleaners etch marble, travertine, and limestone. Use it only on ceramic/porcelain tile surroundings.
What to skip
- Chlorine bleach on colored grout — even diluted, it gradually removes color and weakens the binder.
- Steam cleaners on natural stone surrounds — thermal shock can crack.
- Grout pens as a first resort — they're a cosmetic fix, not a cleaning solution. Clean first; use pens only if cleaned grout stays visibly discolored.
FAQ
How often should I clean grout?
Shower grout: weekly spray-down with a diluted hydrogen peroxide or oxygen bleach spray, and a monthly scrub. Kitchen backsplash: monthly. Floor grout: monthly scrub when mopping.
Can I clean grout without scrubbing?
Not effectively. Chemical products loosen stains but mechanical scrubbing removes them. There is no soak-only solution for stained grout.
My grout is gray — is it clean but just stained permanently?
Possibly. If grout was white before and is now gray, years of unsealed use may have permanently discolored the surface layer. A grout colorant/stain can restore uniform color after deep cleaning.
What is the easiest tool for grout scrubbing?
An electric toothbrush (old, dedicated to cleaning) for bathroom grout. A drill brush attachment or oscillating tool for floors.
Where to go next