Domakihub How to Whiten Grout and Keep It Looking Clean
Restore dingy tile grout to bright white with household supplies and the right technique.
Reviewed by Domakihub cleaning pros · 2026-06-23 · 4 min read
Grout lines are narrow, porous, and relentless at trapping grime — in Greek homes, holiday rentals, and hotel bathrooms they often turn grey or brown long before the tiles themselves show any wear. The video above walks you through the process visually, while the guide below breaks it into clear, repeatable steps you can follow with supplies from any supermarket. Whether you are preparing a rental for the summer season or refreshing a family bathroom, a couple of hours is all it takes to bring white grout back to life.
Why Grout Discolours So Quickly
Grout is a cement-based material with a rough, open surface that absorbs moisture, soap residue, cooking grease, and airborne dirt on contact. In coastal climates like much of Greece the combination of humidity, hard water minerals, and salt air accelerates staining further, which is why grout in bathrooms and outdoor terraces can look years older than it actually is.
Mould and mildew compound the problem in poorly ventilated spaces. The dark patches you see in shower corners are usually biological growth, not just dirt, and they need a different treatment from ordinary surface staining.
Choosing the Right Method for Your Grout
For surface staining that has built up over weeks or months, a paste of baking soda and hydrogen peroxide is highly effective and safe for both tiles and grout. For deeper biological staining (black or pink patches), a diluted bleach solution applied with a stiff brush will kill the mould at the root. For grout that has been scrubbed clean but remains permanently discoloured, a grout pen or liquid grout paint restores the colour without relaying tiles.
Always test any cleaning solution on an inconspicuous corner first, particularly on natural stone tiles such as marble or travertine, which are common in Greek properties and can be damaged by acid-based cleaners.
Steps to Whiten Grout
- 1
Clear the area and protect surfaces
Remove bath mats, toiletries, or any items that might absorb cleaning chemicals. Ventilate the room by opening a window or running the extractor fan. If you are working near coloured grout that you do not want lightened, mask the edges with painter's tape. Put on rubber gloves before you begin.
- 2
Apply a baking soda paste to the grout lines
Mix three parts baking soda with one part hydrogen peroxide (3% pharmacy grade) to form a thick paste. Spread it directly onto the grout lines using an old toothbrush or a dedicated grout brush. Work in small sections of about half a metre at a time so the paste does not dry out before you can scrub it.
- 3
Scrub firmly along each grout line
Using the stiff-bristled brush, scrub back and forth along each grout line with firm, short strokes. Apply enough pressure to work the paste into the pores of the grout rather than just sitting on the surface. For mould staining, spray a diluted bleach solution (one part bleach to ten parts water) over the paste before scrubbing.
- 4
Rinse thoroughly and inspect
Rinse the entire surface with clean water, using a sponge or handheld shower head to remove all paste residue. Dry the area with a clean cloth and check the results in good light. Repeat the scrub on any lines that are still noticeably discoloured — a second application is usually enough for persistent stains.
- 5
Seal the grout to lock in the result
Once the grout is fully dry (allow at least 24 hours), apply a grout sealer with a narrow applicator brush or sealant pen along each line. Sealing closes the porous surface so future dirt sits on top rather than soaking in, cutting your next cleaning job down to a quick wipe. Reapply sealer every 12 to 18 months in high-traffic bathrooms.
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FAQ
- Can I whiten coloured grout, or only white grout?
- The cleaning methods described here work on any grout colour — they remove staining without permanently changing the original colour. If you want to change a beige or grey grout to white, use a grout paint or grout pen specifically labelled for colour change rather than a cleaner.
- Is bleach safe to use near marble or terracotta tiles?
- No. Bleach and strongly alkaline cleaners can etch the surface of natural stone and unglazed terracotta. For these tile types, stick to the baking soda and hydrogen peroxide paste and rinse quickly. For stubborn mould on natural stone, use a stone-safe mould remover available at specialist tile shops.
- How often should grout be cleaned in a holiday rental?
- At minimum, scrub grout at the start and end of each rental season — typically April and October in Greece. For high-occupancy rentals with heavy bathroom use, a lighter clean between guest stays using a daily shower spray will prevent heavy buildup and keep the property looking professional.