How to Clean Grout in Tiles — The Complete Step-by-Step Guide

Dirty grout is one of the most common complaints about tiled surfaces — and one of the most avoidable. Grout is porous by nature, which means it absorbs moisture, grease, soap residue, and bacteria over time. Surface wiping doesn't remove what's absorbed into the grout structure. The methods in this guide do.

This guide covers every practical approach to cleaning grout — from baking soda and vinegar for light household maintenance through to steam cleaning and commercial-grade methods for heavily soiled floors and high-traffic commercial spaces. It also covers what causes grout to get dirty, which methods suit which tile types, how to protect grout after cleaning, and when the job needs professional equipment rather than a toothbrush.

How to Clean Grout in Tiles — Methods, Tile Types, and Commercial Cleaning

Why Grout Gets Dirty So Fast

Understanding why grout stains and darkens explains why some cleaning methods work and others don't.

Moisture and humidity — bathrooms, kitchens, and laundries create the ideal conditions for mould and mildew growth. Steam, splashes, and condensation settle into grout lines and feed microbial growth that ordinary wiping doesn't remove. Once mould establishes in porous grout it requires targeted treatment rather than general surface cleaning.

Grease and food residue — in kitchens, airborne grease particles settle onto horizontal grout lines and gradually build up into a yellow-brown layer. Heat from cooking accelerates this process. Kitchen grout requires degreasing rather than simple cleaning.

Soap scum and mineral deposits — in showers, soap combines with the calcium and magnesium in hard water to form a sticky residue that bonds to grout surfaces. In areas with hard water this buildup is rapid and requires acid-based treatment to dissolve the mineral component.

Foot traffic — on tiled floors, fine dirt particles from shoes get ground into grout lines with every step. This mechanical abrasion also opens the pore structure of the grout over time, making it more absorbent and harder to clean without sealing.

Tools and Supplies to Have Ready

Having the right tools before you start saves time and produces better results. Applying the right cleaning agent to grout and then scrubbing with an inadequate brush wastes both the product and the effort.

Cleaning tools: stiff-bristled grout brush, old toothbrush for tight areas, microfibre cloths, spray bottle, bucket of warm water, rubber gloves, kneeling pad for floor work.

Cleaning agents — matched to the contamination type: baking soda for general maintenance, white vinegar for mineral deposits and soap scum (ceramic and porcelain only), hydrogen peroxide 3% for brightening and mould, commercial alkaline grout cleaner for heavy grease and commercial-scale cleaning, oxygen-based bleach for deeply stained white grout.

Important: never mix bleach with vinegar or with ammonia-based products. The chemical reaction produces toxic gas. Use one product at a time and rinse thoroughly before applying a different cleaning agent.

Method 1 — Baking Soda Paste for General Maintenance

Baking soda is a mild abrasive that lifts surface contamination without damaging grout or tile surfaces. It's the right starting point for grout that's moderately dirty but not heavily stained or mouldy.

1. Mix baking soda with water to form a thick paste — approximately 3 parts baking soda to 1 part water
2. Apply the paste directly to grout lines using a brush or your finger
3. Leave for 10–15 minutes to allow the paste to work into the grout surface
4. Scrub firmly with a grout brush, working along the grout line rather than across it
5. Rinse thoroughly with warm water and wipe dry with a microfibre cloth

This method suits bathrooms and kitchens with general buildup and regular maintenance cleaning. For more stubborn staining, move to the vinegar or hydrogen peroxide methods below.

Method 2 — Vinegar and Baking Soda for Mineral Deposits and Soap Scum

The combination of baking soda and white vinegar creates a fizzing reaction that helps lift mineral deposits, soap scum, and surface mould from grout lines. This method is effective on ceramic and porcelain tiles only — never use vinegar on natural stone.

1. Apply baking soda paste to the grout lines
2. Spray white vinegar directly over the paste — the fizzing reaction begins immediately
3. Leave for 5–10 minutes while the reaction works into the grout
4. Scrub with a grout brush
5. Rinse thoroughly and dry completely — residual moisture accelerates mould regrowth

Do not use on: marble, travertine, limestone, slate, or any natural stone tile. Vinegar's acidity etches natural stone surfaces, causing permanent surface damage that cannot be reversed without professional resurfacing.

Method 3 — Hydrogen Peroxide for Whitening and Mould

Hydrogen peroxide at 3% concentration — the standard chemist version — is an effective grout brightener and mould treatment that's safer than chlorine bleach for most tile types. It's particularly effective on white or light-coloured grout that has darkened over time.

1. Pour 3% hydrogen peroxide into a spray bottle
2. Spray directly onto grout lines until saturated
3. Leave for 10–15 minutes — longer for established mould
4. Scrub with a grout brush
5. Rinse with clean water and dry thoroughly

For stubborn mould, make a paste of baking soda and hydrogen peroxide rather than water and apply as per Method 1. The peroxide replaces the water component and adds oxidising power to the abrasive action of the baking soda.

Method 4 — Steam Cleaning

Steam cleaning is one of the most effective methods for grout — particularly for commercial spaces, households with children or allergy sufferers, and environments where chemical residue is a concern. Steam penetrates the porous grout structure, loosening dirt, bacteria, and grease through heat and pressure rather than chemical action.

1. Fill the steam cleaner with water according to the manufacturer's instructions
2. Attach the grout brush nozzle or narrow jet attachment
3. Run steam slowly along each grout line — moving too fast reduces effectiveness
4. Wipe away loosened dirt immediately with a microfibre cloth before it resettles
5. Work in small sections to ensure the steam and wiping sequence stays ahead of any drying

Steam is chemical-free, effective on all tile types including natural stone, and kills bacteria and mould without leaving chemical residue. For commercial kitchens and food service environments where chemical residue on floors is a compliance concern, steam is the preferred deep-cleaning method for tiled surfaces.

Browse our commercial steam cleaner range here.

Method 5 — Commercial-Grade Grout Cleaners

When natural methods aren't penetrating deeply stained or heavily contaminated grout, commercial-grade grout and tile cleaners are the appropriate next step. These products are formulated with higher concentrations of active cleaning agents than consumer products and include pH-matched formulations for different tile and grout types.

1. Select the appropriate product for your tile type — alkaline cleaners for ceramic and porcelain, pH-neutral for natural stone
2. Apply the cleaner to grout lines and allow the specified dwell time — typically 5–15 minutes
3. Scrub with a stiff grout brush
4. Rinse thoroughly with clean water — commercial cleaners require complete rinsing to prevent residue buildup that attracts dirt
5. Dry with a clean cloth

Always follow the manufacturer's dilution and dwell time instructions. Over-concentration doesn't improve results and can damage grout or tile surfaces on extended contact.

Tile Type Matters — Matching Method to Material

Ceramic and porcelain tiles — the most forgiving tile type for cleaning. Handle most cleaning agents well including dilute vinegar, baking soda, hydrogen peroxide, steam, and most commercial cleaners. Suitable for all five methods above.

Natural stone — marble, travertine, limestone, slate — never use acidic cleaners including vinegar, lemon juice, or acid-based commercial products. These etch the stone surface permanently. Use only pH-neutral stone-safe cleaners and steam. For heavily stained natural stone grout, professional treatment is the safest approach.

Glass tiles — use non-abrasive brushes only to avoid scratching. Baking soda paste is too abrasive for glass tile surfaces. Use mild liquid cleaners and a soft brush or microfibre cloth.

Unglazed and porous tiles — these absorb cleaning products more readily than glazed surfaces. Avoid excessive dwell time with any chemical cleaner and rinse thoroughly. Steam is particularly effective for porous tile types as it cleans without leaving chemical residue in the tile surface.

Floor Grout vs Wall and Shower Grout

The same methods apply to both but with different practical considerations.

Floor grout — foot traffic grounds fine dirt particles deep into the grout structure. Vacuum or dry sweep first to remove loose surface debris before applying any wet cleaning method. Work in manageable sections — attempting to clean an entire tiled floor in one pass reduces effectiveness and makes rinsing difficult. For large commercial tiled floor areas, mechanical cleaning with a floor scrubber fitted with an appropriate brush head is significantly more practical than manual scrubbing.

Wall and shower grout — primary contamination is soap scum, mineral deposits, and mould rather than tracked dirt. Spray-on application works well on vertical surfaces. Ensure thorough rinsing after every cleaning session — chemical residue left on shower grout accelerates soap scum buildup and can contribute to surface degradation over time.

Removing Mould and Mildew from Grout

Mould in grout is a health concern beyond aesthetics — it indicates a moisture problem that will recur unless the source is addressed. Cleaning the visible mould is necessary but not sufficient if condensation, poor ventilation, or water ingress is feeding regrowth.

1. Spray hydrogen peroxide or oxygen-based bleach directly onto the affected grout
2. Leave for 15–20 minutes — longer contact time is more effective on established mould than higher concentration
3. Scrub with a grout brush
4. Rinse thoroughly and dry the area completely — residual moisture feeds regrowth
5. Improve ventilation in the space after cleaning — a bathroom exhaust fan running during and after showering reduces the moisture level that feeds mould

For black mould that has penetrated deeply into the grout structure or recurs rapidly after cleaning, professional mould remediation or grout replacement is likely the more appropriate response than continued surface cleaning.

Cleaning Grout in Commercial and High-Traffic Areas

In offices, gyms, restaurants, hotels, and schools, grout gets dirty significantly faster than in residential environments. Higher foot traffic, food and beverage spills, chemical cleaning products, and frequent wet mopping all accelerate grout staining and microbial growth. Manual scrubbing on hands and knees isn't practical at commercial scale — mechanical cleaning is the appropriate approach.

Compact floor scrubbers with grout brush attachments — compact floor scrubbers fitted with appropriate brush heads cover large tiled floor areas efficiently, applying solution and agitating grout lines mechanically. For commercial facilities cleaning tiled floors regularly, a floor scrubber reduces labour time compared to manual scrubbing and produces more consistent results across large areas.

Browse compact floor scrubbers here.

Commercial steam cleaners — steam penetrates porous grout and removes contamination without chemicals, which is particularly relevant in food service environments where chemical residue on floors is a hygiene and compliance concern. The Steamvac range delivers commercial-grade steam cleaning across tiled surfaces including kitchen floors, dining areas, and restrooms.

Browse commercial steam cleaners here.

Commercial maintenance schedule for tiled floors:

• Daily — spot clean spills immediately before contamination sets into grout
• Weekly — full mechanical floor scrub with appropriate cleaning solution
• Monthly — steam clean or deep mechanical scrub targeting grout lines specifically
• Annually — reseal grout in high-traffic tiled areas to reduce absorption and simplify ongoing maintenance

How to Protect Grout After Cleaning — Sealing

Cleaning grout removes contamination from the surface and the upper layer of the pore structure. Sealing grout after cleaning fills those pores with a penetrating sealer that prevents water, oils, and dirt from absorbing as readily. This doesn't make grout maintenance-free but it significantly extends the interval between deep cleans and makes surface cleaning more effective.

1. Ensure grout is completely clean and fully dry before sealing — sealing over contaminated or damp grout traps the problem rather than solving it
2. Apply grout sealer with a brush, roller, or purpose-built applicator bottle along each grout line
3. Wipe excess sealer from tile surfaces immediately before it dries — dried sealer on tile surfaces leaves a hazy residue
4. Allow the sealer to cure fully — typically 24 hours — before exposing the surface to water or foot traffic

Reseal every 6–12 months in residential applications and every 3–6 months in high-traffic commercial environments. Colour-enhanced sealers are available for grout that is clean but permanently discoloured — these restore a uniform appearance without requiring re-grouting.

Common Mistakes That Damage Grout or Make Staining Worse

• Using metal brushes or abrasive scourers — scratches the grout surface, increases porosity, and accelerates future staining
• Applying acidic cleaners to natural stone — permanently etches the stone surface
• Skipping the rinse step — cleaning product residue left in grout attracts dirt and accelerates restaining
• Leaving surfaces wet after cleaning — residual moisture feeds mould regrowth within 24–48 hours in a bathroom environment
• Mixing cleaning products — bleach and vinegar produce chlorine gas, bleach and ammonia produce chloramine gas, both are toxic
• Cleaning before sweeping or vacuuming — wet cleaning over loose surface dirt grinds it deeper into grout rather than removing it

How Often Should You Clean Grout?

Frequency depends on the environment, traffic level, and moisture exposure. As a general guide:

• Light weekly cleaning — wipe down tiled surfaces and grout lines with a suitable cleaner to prevent buildup between deep cleans
• Deep clean every 3–4 months — full scrub using one of the methods above depending on the contamination type
• Reseal once per year in residential applications, more frequently in commercial or high-moisture environments

Consistent light maintenance is significantly more effective than infrequent intensive cleaning — grout that is regularly wiped down never reaches the level of contamination that requires heavy chemical treatment or professional intervention.

When to Call a Professional

Some grout problems are beyond what DIY methods can address effectively:

• Grout that is crumbling, cracking, or missing sections — this requires re-grouting rather than cleaning
• Deeply embedded black mould that recurs rapidly after cleaning — may indicate water ingress behind the tiles requiring investigation
• Permanently discoloured grout where the staining has penetrated the full depth of the grout — professional high-pressure steam extraction or colour sealing may restore appearance where surface methods have failed
• Large commercial tiled areas where manual cleaning is not practical — professional cleaning contractors with appropriate mechanical equipment are more efficient than attempting to scale manual methods

Related articles and links:

• Steamvac commercial steam cleaners
• Compact floor scrubbers
• Commercial floor scrubbers and sweepers
• What is a commercial floor scrubber and do you need one?
• How often should you scrub commercial floors?