How to Clean Grout and Remove Mould in Bathrooms and Showers

Written by Nestor Dos Santos, Owner, TN Stone Pty Ltd · Updated 13 July 2026

Dirty grout can make an otherwise clean bathroom look old, unhygienic and poorly maintained. In showers and wet areas, grout often collects soap scum, moisture, mildew and black mould, especially where ventilation is poor. In this guide, we explain how to clean grout safely, how to remove mould, and when it may be better to repair or replace the grout instead of cleaning it again.

Why grout gets dirty and mouldy

Grout is often more porous than the tile around it, which means it can hold onto moisture, soap residue, body oils and grime more easily. In bathrooms and showers, this creates the perfect environment for mildew and mould growth.

Poor airflow, damp corners, slow drying times and soap scum buildup all make the problem worse. That is why shower grout usually gets dirtier faster than grout in dry rooms.

Best way to clean grout for general dirt and grime

For normal bathroom buildup, the safest starting point is a gentle but effective scrub-based clean.

1. Wet the grout lightly with warm water.
2. Apply your chosen grout cleaner or a mild cleaning solution.
3. Use a grout brush or old toothbrush to scrub the joints.
4. Rinse thoroughly with clean water.
5. Dry the area with a cloth or towel.

In many cases, regular manual scrubbing is one of the most effective ways to remove early grime and stop heavier mould buildup from taking hold.

How to remove mould from grout

If black spots or mildew are already visible, the cleaning method usually needs to be more targeted. Common approaches people use include:

• Bicarbonate soda paste and scrubbing
• Vinegar-based cleaning for some situations
• Hydrogen peroxide treatments
• Steam cleaning
• Commercial mould or grout cleaners

Different households prefer different methods, but the key idea is to loosen the mould, scrub the grout properly, rinse well, and then dry the area fully so moisture does not remain trapped.

A simple grout-cleaning method for showers

One common home-cleaning method is to make a paste from bicarbonate soda and water, apply it to the grout, scrub with a small brush, then rinse the area clean. Some people also use vinegar in combination with bicarbonate soda, but any acidic cleaner should be used carefully and tested first because nearby natural stone surfaces can be damaged by acids.

If your shower includes marble, limestone, travertine or any other natural stone, do not use vinegar or acidic cleaners on or around those materials. See our How to Clean Natural Stone Without Damaging It guide for stone-safe methods.

Can steam cleaning help?

Yes, steam cleaning can be a useful low-chemical option for regular grout maintenance and light mould removal. High-temperature steam can help loosen dirt, soap scum and mildew from grout lines, especially when followed by wiping and drying the area.

Steam cleaning is often best as part of regular maintenance rather than as a cure for severely stained or deeply contaminated grout.

What if mould keeps coming back?

If the mould returns quickly after cleaning, the problem is often bigger than surface dirt alone. Common causes include:

• Poor bathroom ventilation
• Grout that stays wet for long periods
• Soap scum and residue left behind after showers
• Old or unsealed grout absorbing moisture
• Failing silicone in corners and joints

In these cases, prevention matters just as much as cleaning. See our When to Use Caulking vs Grout guide if corner silicone is part of the problem.

How to stop grout mould from coming back

• Use the exhaust fan during and after showers
• Open windows or doors where possible to improve airflow
• Squeegee or towel-dry shower walls after use
• Keep wet towels and damp items from sitting in the bathroom
• Clean soap scum regularly before it builds up
• Seal cement-based grout if appropriate
• Replace failing silicone around corners, baths and shower bases

These steps will not make a bathroom completely mould-proof, but they can reduce how quickly mould returns and make deep cleaning less frequent.

Should you use bleach?

Some people use bleach-based products for mould in grout, and bleach can be effective in some cases. However, it needs to be used carefully, with good ventilation, correct dilution where required, and attention to surrounding materials.

Bleach is not always the best first option, especially if the bathroom contains natural stone or if the grout is already deteriorating. Always read the label, follow safety directions, and test products carefully.

When cleaning is not enough

Sometimes grout is too far gone for cleaning alone. If the mould has penetrated deeply, the grout is crumbling, or the staining is permanent, repeated scrubbing may not solve the problem.

In that situation, the better long-term solution may be:

• Removing and replacing the grout
• Replacing mouldy silicone in corners or around fittings
• Checking waterproofing or leak issues if moisture problems are ongoing

For regrouting with a more mould-resistant product, see our Best Grout for Showers in Australia guide.

Signs you may need regrouting

• The grout is cracked or missing in places
• Black mould keeps returning quickly after cleaning
• Stains remain after repeated cleaning attempts
• The grout feels soft, loose or powdery
• The shower still smells musty after cleaning

Regrouting is often the better choice when the grout has become permanently discoloured or structurally weak.

Best cleaning tools for grout

• Grout brush
• Old toothbrush for tight areas
• Microfibre cloths
• Steam cleaner for maintenance
• Gloves and eye protection when using stronger products

Avoid very aggressive metal tools or abrasive pads unless the product specifically calls for them and the tile finish can handle it.

How often should you clean shower grout?

Light cleaning every week or two is usually much easier than waiting for heavy mould buildup. Wiping the shower down a few times a week and doing a more thorough grout scrub regularly can make a big difference.

In family bathrooms with frequent use, more regular maintenance usually means less need for harsh cleaning later.

When to call a professional

If your grout is heavily mouldy, cracked, stained beyond cleaning, or part of a larger bathroom moisture issue, it may be time to get professional help. This is especially true if the shower corners, silicone joints or waterproofing may also be failing.

TN Stone provides tiling, regrouting, sealing and bathroom renovation services across Melbourne and the western suburbs, including Brookfield, Werribee, Caroline Springs, Footscray and surrounding areas.

Frequently asked questions

What is the best way to clean shower grout?

For most showers, the best starting point is a grout brush, warm water and a suitable grout cleaner or gentle cleaning paste, followed by a thorough rinse and full drying of the area.

How do I remove black mould from grout?

Black mould often needs targeted scrubbing with a mould treatment, bicarbonate paste, steam cleaning, or another grout-safe method, plus better drying and ventilation afterward.

Can mouldy grout be saved?

Sometimes yes, especially if the mould is only on the surface. But if the mould is deeply embedded or the grout is deteriorating, regrouting may be the better option.

Why does mould keep coming back in my shower?

Usually because of trapped moisture, poor ventilation, soap scum buildup, or old grout and silicone that are holding water and contamination.

Should I replace silicone as well as clean grout?

In many cases, yes. If the silicone is mouldy, cracked or peeling, it may need replacement because cleaning alone may not solve the problem.