Dirty grout can make even the cleanest tiles look old and grimy. Over time, grout absorbs dirt, soap scum, and moisture — turning from white or coloured to dark grey or brown. This guide shows you how to clean grout effectively using natural ingredients and professional techniques.

Why grout gets dirty: Grout is porous, so it absorbs spills, soap residue, and moisture. In bathrooms, it also attracts mould and mildew.

What You'll Need

  • Baking soda
  • White vinegar
  • Hydrogen peroxide (3%)
  • Dish soap
  • Stiff-bristled brush (an old toothbrush works perfectly)
  • Spray bottle
  • Microfiber cloths
  • Steam cleaner (optional, but powerful)
  • Grout pen or sealer (for after cleaning)

Method 1: Baking Soda & Vinegar (Best for Light to Moderate Grime)

This natural method is effective for regular maintenance and lighter discolouration.

1

Make a Baking Soda Paste

Mix baking soda with a small amount of water to form a thick, spreadable paste — like toothpaste consistency.

2

Apply the Paste

Spread the paste over the grout lines using a brush or your finger (wear gloves).

3

Spray with Vinegar

Spray white vinegar over the paste. The reaction will create a fizzing foam that lifts dirt from the grout pores.

Pro Tip: The fizzing means it's working! Let it bubble for 5-10 minutes.
4

Scrub and Rinse

Scrub vigorously with a stiff brush, then rinse with water and wipe dry.

Method 2: Baking Soda & Hydrogen Peroxide (For Stubborn Discolouration)

This method is more powerful — perfect for heavily stained grout that vinegar alone won't touch.

1

Make a Stronger Paste

Mix baking soda with hydrogen peroxide (3%) instead of water. The consistency should be like toothpaste.

2

Apply and Let Sit

Spread the paste over the grout lines. Let it sit for 10-15 minutes — the hydrogen peroxide bleaches stains.

Test First: Hydrogen peroxide can lighten coloured grout. Always test on an inconspicuous area first.
3

Scrub and Rinse

Scrub with a stiff brush, then rinse thoroughly with water.

Method 3: Bleach Solution (For Severe Mould in Grout)

For grout with black mould or years of built-up grime, bleach may be necessary.

1

Mix Bleach Solution

Mix 1 part bleach with 4 parts water in a spray bottle.

Ventilate: Open windows and wear gloves and eye protection. Never mix bleach with vinegar or ammonia.
2

Apply and Wait

Spray the solution onto grout lines. Let it sit for 5-10 minutes.

3

Scrub and Rinse Thoroughly

Scrub with a brush, then rinse multiple times with water to remove all bleach residue.

Method 4: Steam Cleaning (Professional-Grade Results)

Steam cleaners use high-temperature steam to dissolve dirt without chemicals. Ideal for large areas.

1

Set Up the Steamer

Fill your steam cleaner with water according to manufacturer instructions.

2

Steam the Grout

Direct the steam nozzle along grout lines. The heat and moisture will loosen dirt immediately.

3

Wipe Away Residue

Wipe with a microfiber cloth as you go. For stubborn spots, use a brush attachment.

Pro Tip: Steam cleaners are available to rent if you don't want to buy one — or book a professional service.

Professional Tools for Grout Cleaning

Grout Brush

  • Stiff nylon bristles are best — metal brushes can scratch tiles
  • A narrow brush fits perfectly in grout lines

Electric Grout Cleaner (Detailing Brush)

  • Battery-powered brush that scrubs for you — saves elbow grease on large areas
  • Available online for £20-40

Grout Pen

  • After cleaning, a grout pen restores colour to faded grout
  • Available in white, light grey, and dark grey

How to Prevent Grout from Getting Dirty Again

  • Seal your grout: Apply a penetrating grout sealer every 1-2 years. Sealed grout repels water and stains.
  • Squeegee after showers: Removing water prevents mould in bathroom grout.
  • Wipe spills immediately: Don't let liquids sit on grout lines.
  • Ventilate bathrooms: Use extractor fans to reduce moisture.
  • Clean grout monthly: A quick scrub prevents buildup.
Pro Tip: Seal grout 48 hours after deep cleaning — this gives it time to dry completely. Wet sealer won't absorb properly.

Removing Grout Stains by Type

Red Wine or Coffee Stains

  • Blot immediately, then use hydrogen peroxide paste

Soap Scum (Bathroom Grout)

  • Use equal parts vinegar and water, then scrub

Rust Stains

  • Lemon juice or a commercial rust remover — but test first

Mould/Mildew

  • Bleach solution or undiluted vinegar works best
Never use: Acidic cleaners (like straight vinegar) on unsealed grout — acid dissolves grout over time. If you use vinegar, rinse thoroughly.
When to regrout instead of clean: If grout is crumbling, cracking, or falling out, cleaning won't help. Remove and replace the grout entirely.