Grout is the Achilles heel of every shower. While your tiles stay gleaming, the grout between them slowly darkens with soap scum, body oils, mold, and mildew. Finding the best shower grout cleaner saves you hours of frustrating scrubbing and prevents the discoloration that makes even new showers look neglected. I have maintained and restored grout in hundreds of showers over my 30+ year career, and I know what works, what wastes money, and what actually damages grout if you use it wrong.
Table of Contents
Top Grout Cleaning Products
I have tested dozens of grout cleaners over the years. These are the ones that consistently deliver results without damaging the grout or surrounding tile.
Best overall: Zep Grout Cleaner and Brightener. This acidic gel clings to grout lines and whitens stained cement grout in minutes. Apply, wait 3 minutes, scrub with a grout brush, and rinse. The gel consistency means it stays on vertical grout lines instead of running off. It restores heavily discolored white and light-colored grout better than any other product I have used. About $8-10 for a 32-ounce bottle. Do not use on natural stone or colored grout.
Best for mold and mildew: RMR-86 Instant Mold and Mildew Stain Remover. This professional-strength spray eliminates black mold stains from grout within seconds — you can watch the discoloration disappear before your eyes. It is sodium hypochlorite-based (bleach), so ventilate well and wear gloves. Extremely effective on white grout. About $12-15 per bottle.
Best oxygen-based cleaner: OxiClean Versatile Stain Remover. Dissolve OxiClean powder in hot water and apply to grout with a brush. The oxygen-based formula lifts stains and brightens grout without chlorine bleach fumes. Safer for colored grout than bleach-based options. Works more slowly — plan on 15-30 minutes of dwell time. About $8-12 for a tub that lasts for many cleanings.
Best for natural stone showers: Aqua Mix Heavy-Duty Tile and Grout Cleaner. A concentrated alkaline cleaner that is safe for natural stone tiles while effectively cleaning grout. It does not contain acid, which makes it safe for marble, travertine, and limestone showers. About $15-20 for a concentrated quart.
Best pen-style applicator: Grout Pen by Rainbow Chalk Markers. Not a cleaner but a cosmetic solution. This paint pen covers stained grout with a fresh white (or colored) coating that makes grout look brand new. It is a quick fix rather than a deep clean, but the results are immediate and last several months in a shower before needing reapplication. About $8-12 per pen.
Best budget option: Baking soda and hydrogen peroxide (DIY). Mix baking soda and hydrogen peroxide into a paste, apply to grout, wait 15 minutes, scrub, and rinse. Free if you already have the ingredients, and it works surprisingly well on moderate staining. More on DIY recipes below.
Bleach vs Oxygen-Based Cleaners
This is the fundamental choice in grout cleaning, and each approach has clear advantages and limitations.
Chlorine bleach (sodium hypochlorite). The active ingredient in products like RMR-86, Clorox Clean-Up, and household bleach. Bleach kills mold and mildew on contact, whitens stained grout rapidly, and disinfects surfaces. It works fast — most bleach-based grout cleaners show results in 1-5 minutes.
Downsides: strong fumes that require ventilation, can discolor colored grout, may corrode metal fixtures over time with repeated use, irritates skin and eyes, and is not safe for natural stone. Bleach also does not remove soap scum or mineral deposits — it only whitens and disinfects. If your grout is stained by hard water minerals rather than mold, bleach will not help.
Oxygen-based cleaners (sodium percarbonate). Found in OxiClean, Biokleen Oxygen Bleach, and similar products. Oxygen cleaners break down into hydrogen peroxide and soda ash when dissolved in water, creating an oxidizing solution that lifts stains and brightens grout gently.
Oxygen cleaners are slower-acting (15-60 minutes vs 1-5 minutes for bleach) but gentler on grout, safer for colored grout, less harmful to fixtures, produce no chlorine fumes, and are safe for septic systems. They handle soap scum stains and organic discoloration well but may not fully eliminate deep black mold staining.
My recommendation: Use oxygen-based cleaners for routine grout maintenance every 2-4 weeks. Reserve chlorine bleach products for periodic deep cleaning of white grout with mold issues, no more than once a month. Alternating between the two gives you the best of both approaches without overexposing your grout to harsh chemicals.
DIY Grout Cleaning Recipes
These homemade solutions work genuinely well. I use them in my own home and recommend them to clients who prefer to avoid commercial chemicals.
The all-purpose grout cleaner. Mix 1/2 cup baking soda, 1/4 cup hydrogen peroxide (3%), and 1 teaspoon liquid dish soap into a paste. Apply to grout lines with an old toothbrush, let it sit for 15 minutes, scrub, and rinse. This handles most soap scum and light mold staining. Safe for all grout colors and tile types.
The heavy-duty whitener. Mix baking soda and bleach into a thick paste. Apply to white grout only, let it sit for 10-15 minutes, scrub with a stiff brush, and rinse thoroughly. Wear gloves and ensure ventilation. This rivals commercial bleach products for whitening power. Not safe for colored grout or natural stone.
The oxygen soak. Dissolve 2 tablespoons of OxiClean powder in 2 cups of hot water. Apply to grout with a spray bottle or brush. Let it work for 30-60 minutes, keeping the grout wet by respraying as needed. Scrub and rinse. The extended dwell time allows the oxygen to penetrate deep into grout pores.
The vinegar spray (for mineral stains). Spray undiluted white vinegar on grout stained by hard water deposits. Wait 10-15 minutes, scrub with a grout brush, and rinse. Vinegar dissolves calcium and mineral deposits that bleach and oxygen cleaners cannot touch. Do not use on grout adjacent to natural stone tiles — the vinegar can etch the stone. Also, never mix vinegar with bleach — the combination creates toxic chlorine gas.
The preventive spray. Mix 1 cup water, 1 cup white vinegar, and 1 tablespoon dish soap in a spray bottle. Use as a weekly maintenance spray on grout lines after cleaning. The soap helps repel soap scum, and the vinegar discourages mold growth. For natural stone showers, replace the vinegar with rubbing alcohol.
Steam Cleaning Grout
Steam cleaning is the most effective chemical-free method for cleaning shower grout, and it has become my preferred approach for regular maintenance.
A handheld steam cleaner produces steam at 200-300°F, which is hot enough to kill mold, mildew, and bacteria on contact, loosen soap scum and body oil deposits, and dissolve grime embedded in grout pores — all without any chemicals.
How to steam clean shower grout: Attach the small grout-cleaning nozzle or brush attachment. Hold the steam nozzle 1-2 inches from the grout line and move slowly along the joint. Work in 2-3 foot sections, wiping loosened grime with a microfiber cloth as you go. Follow up with a complete rinse.
Recommended steam cleaners: The McCulloch MC1275, Dupray Neat, and Bissell SteamShot are all effective for shower grout. Look for at least 40 PSI of steam pressure and a unit that heats up in under 5 minutes. Expect to pay $40-100 for a capable handheld unit.
Limitations: Steam alone may not remove heavy mold staining that has penetrated deep into grout. In these cases, use steam as a first pass to kill the mold and loosen surface staining, then follow up with a targeted cleaner for remaining discoloration.
Steam is safe for all tile types including natural stone, which makes it the ideal cleaning method for marble and travertine showers where chemical options are limited.
Mold vs Mildew on Grout
People use these terms interchangeably, but understanding the difference helps you choose the right treatment.
Mildew is a surface fungus that appears as gray, white, or light brown patches on grout and caulk. It grows on the surface and is relatively easy to clean. Mildew responds well to vinegar, hydrogen peroxide, and most bathroom cleaners. Regular cleaning keeps it under control.
Mold appears as black, dark green, or dark brown spots and patches. It penetrates deeper into grout pores and can develop roots (hyphae) that extend below the visible surface. Black mold on grout requires more aggressive treatment — bleach-based products, steam cleaning, or oxygen cleaners with extended dwell times.
Key differences in treatment:
- Mildew wipes away with light cleaning. Mold requires scrubbing and targeted products.
- Mildew rarely survives a standard weekly cleaning. Mold can persist through multiple cleanings if it has penetrated deeply.
- Mildew recurs quickly in humid conditions but is easily re-cleaned. Mold recurrence after thorough cleaning suggests a moisture problem behind the tile that needs professional attention.
When mold keeps coming back: If mold returns within days of cleaning despite good ventilation and regular maintenance, the issue is likely moisture behind the tile. Failed waterproofing, cracked grout, or missing caulk can allow water to penetrate the wall cavity, creating a mold-friendly environment that surface cleaning cannot address. In this case, professional inspection is warranted.
Prevention Strategies
Preventing grout discoloration is far less work than removing it. These habits keep shower grout looking fresh between cleanings.
Ventilation is everything. Run your bathroom exhaust fan during every shower and for 20-30 minutes after. If your fan is old and weak, replace it. A good exhaust fan rated at 80-110 CFM costs $80-150 and is the single best investment for shower longevity. Without adequate ventilation, no cleaning routine will keep mold at bay.
Squeegee habit. Squeegee all tile walls and the glass door after the last shower of the day. This removes 90% of the standing water that feeds mold and deposits soap scum on grout. Thirty seconds of squeegeeing saves hours of scrubbing over the course of a year.
Daily spray. A quick spray of daily shower cleaner (commercial or DIY) after squeegeeing adds a protective layer that inhibits buildup. This is especially effective in hard water areas.
Seal your grout. Sealed grout resists moisture, mold, and staining far better than unsealed grout. More on this in the next section.
Address damage immediately. Cracked grout and gaps in caulk let moisture into the wall. Repair these as soon as you notice them. Keeping the grout and caulk intact is preventive maintenance that avoids major problems.
Consider epoxy grout for new installations. If you are building a new shower or regrouting, epoxy grout eliminates most grout cleaning challenges. It is waterproof, stain-proof, and mold-resistant without sealing. The initial cost and installation difficulty are higher, but the long-term maintenance savings are substantial.
Sealing Shower Grout
Sealing is the most impactful maintenance step you can take for shower grout, yet the majority of homeowners skip it or do not know it is necessary.
Cement-based grout (which includes both sanded and unsanded grout) is porous. Without sealer, it absorbs water, soap, body oils, and mold spores directly into its matrix. Sealed grout repels moisture and contaminants, making it dramatically easier to keep clean and resistant to staining and mold growth.
When to seal: Seal new grout 48-72 hours after installation, once it has fully cured. Reseal every 6-12 months in showers, which experience far more moisture than other tiled areas. Test whether your grout needs resealing by dripping water on a grout line — if it absorbs into the grout and darkens, it is time to reseal. If it beads on the surface, the sealer is still active.
Best grout sealers for showers:
- StoneTech BulletProof Sealer: My top pick. A fluoropolymer-based impregnating sealer that provides maximum stain and moisture protection. Expensive but outperforms everything else. One coat usually suffices.
- Aqua Mix Sealer’s Choice Gold: An excellent water-based penetrating sealer with low odor and easy application. Slightly less protection than BulletProof but more user-friendly. Two coats recommended.
- Miracle 511 Impregnator: A solvent-based penetrating sealer with strong protection and a long track record. Works well on both grout and natural stone. Two coats recommended.
How to apply: Clean the grout thoroughly and let it dry completely (24 hours after cleaning). Apply sealer along the grout lines using the bottle’s applicator tip or a small brush. Wipe excess sealer off the tile surface within 5 minutes to prevent hazing. Apply a second coat after 10-15 minutes if recommended. Allow 24 hours before shower use.
Epoxy grout note: If your shower has epoxy grout, sealing is not necessary. Epoxy grout is inherently non-porous and does not absorb moisture or stains.
When to Regrout
Sometimes cleaning is not enough. Grout that is cracked, crumbling, permanently stained, or deeply mold-infested may need removal and replacement.
Signs you need to regrout:
- Grout is cracking or crumbling in multiple areas
- Grout is missing or receding below the tile surface
- Mold persists despite repeated deep cleaning
- Grout discoloration is too deep for surface cleaning to restore
- Water is seeping behind the tile (visible damage on the wall behind the shower)
Partial vs full regrout: If damage is limited to a few areas, you can remove and replace grout in those sections only. Use a manual grout saw or oscillating multi-tool with a grout-removal blade. Vacuum the joint, apply new grout, and seal. For widespread issues, a full regrout is more practical and gives a uniform appearance.
DIY regrouting cost: About $30-60 in materials (grout removal tool, grout, sealer) plus 4-8 hours of labor for a standard shower. Professional regrouting costs $300-600 for a shower, which is money well spent if you lack the patience for the tedious grout removal process.
If the tile behind the grout shows signs of moisture damage, waterproofing failure, or structural issues, simply regrouting will not solve the problem. In these cases, a full shower rebuild may be necessary. Consult a qualified tile professional for assessment.
Frequently Asked Questions
How often should you clean shower grout?
Light cleaning weekly (spray, scrub grout lines with a brush, rinse) combined with a daily squeegee habit keeps shower grout in good condition year-round. A deeper cleaning with a dedicated grout product every 4-6 weeks addresses any buildup that accumulates despite regular maintenance. If you skip the weekly routine, plan on deep cleaning every 1-2 weeks.
Does bleach damage grout?
Occasional use of diluted bleach on cement grout is safe and effective. However, frequent or prolonged bleach exposure can weaken the cement binders in grout over time, causing it to become powdery and deteriorate faster. Limit bleach-based cleaning to once a month or less, and rinse thoroughly after use. For routine cleaning, use pH-neutral or oxygen-based products instead.
Can you use vinegar on shower grout?
Vinegar is safe for cement-based grout in moderate use. It is effective at dissolving hard water mineral deposits that other cleaners miss. However, avoid vinegar on grout adjacent to natural stone tiles (marble, travertine, limestone) because it will etch the stone. Also never mix vinegar with bleach — this creates dangerous chlorine gas.
What is the fastest way to clean shower grout?
For speed, spray a bleach-based grout cleaner like RMR-86 or Zep Grout Cleaner directly on the grout lines. The stains begin to fade within 1-3 minutes. Scrub briefly with a grout brush and rinse. Total time: about 10 minutes for a standard shower. A drill-brush attachment speeds up scrubbing further. For a chemical-free fast option, a steam cleaner with a grout nozzle is nearly as quick.
Should I use a grout pen to cover stained grout?
Grout pens are a viable cosmetic solution when cleaning cannot fully restore the original grout color. They apply a water-resistant paint layer over the grout surface that makes it look fresh and new. In a shower, grout pen coatings typically last 3-6 months before needing reapplication due to constant moisture exposure. They work best as a temporary refresh between deeper cleaning sessions or as a bridge solution until you are ready to regrout.
