In a London bathroom, grout is the first thing to give the room away. The tiles can be spotless, but if the lines between them have turned grey, brown or speckled with black, the whole room looks tired. Most of the time that grout is not ruined, it is just dirty. Here is how to clean grout and get it close to its original colour, using things you probably already have.
Why grout gets so dirty
Grout is porous. It soaks up soap scum, body oils, limescale and dirty mop water, and in a steamy bathroom it gives mould a perfect place to grow. Because it sits slightly lower than the tiles, a normal wipe goes straight over it. Over months, the colour changes so slowly that most people only notice when they see a patch that has been cleaned.
What you need
- bicarbonate of soda
- white vinegar in a spray bottle
- a stiff grout brush or an old toothbrush
- washing-up liquid
- a bowl of warm water and a clean cloth
- rubber gloves
A proper grout brush, with a narrow, stiff head, saves a lot of time compared with a toothbrush, but either will do the job.
How to clean grout step by step
1. Start with warm water
Scrub a small section with warm water and the brush first. Light surface dirt often comes off with this alone, and it tells you how much work the rest will need.
2. Apply a bicarbonate paste
Mix bicarbonate of soda with a little water into a thick paste and spread it along the grout lines with your finger or the brush.
3. Spray with vinegar
Lightly spray white vinegar over the paste. It will fizz. Leave it for five to ten minutes while it loosens the grime.
4. Scrub along the lines
Scrub in short strokes along each grout line, not across it. Work in small sections, so the paste does not dry out before you get to it.
5. Rinse and dry
Wipe everything down with clean warm water and a cloth, then dry the area. Leaving it wet just invites the mould back.
How to clean grout on floors and walls
Floor grout takes more dirt from shoes and mopping, so it often needs two rounds. Mop the floor first, then work on the grout in sections on your knees with a kneeling pad. For wall grout in the shower, start at the top and work down, so dirty water does not run over lines you have already cleaned.
What about black mould in grout?
Black spots in shower grout are usually mould. Vinegar helps with light patches, so clean grout like this with a window open. If the mould has gone deep, or if it has spread into the silicone sealant around the bath or shower tray, cleaning will only lighten it. At that point the silicone needs cutting out and replacing, and the grout may need raking out and redoing in the worst areas.
Whatever you use, never mix bleach with vinegar or any other cleaning product. The fumes are dangerous.
A word of caution on natural stone
If your tiles are marble, limestone or travertine, skip the vinegar completely. Acid etches natural stone and leaves dull marks that do not polish out. Use warm water, a mild washing-up liquid solution and the brush instead.
Keeping clean grout for longer
- squeegee the shower walls after each use
- run the extractor fan during and after showers, or open a window
- give the grout a quick scrub once a week, so dirt never builds up
- apply a grout sealer once the grout is clean and fully dry, which makes it far less absorbent
When to bring in a professional
Large tiled floors, years of build-up or a bathroom you want spotless before moving out can take a whole day by hand. For bathroom deep cleaning in London, a professional deep cleaning service tackles grout, limescale and soap scum across the whole bathroom and kitchen. Grout is also one of the details inventory clerks look at closely, so it is always part of an end of tenancy cleaning in London.
For a regular clean at home, the paste, the fizz and a good brush will do most of the work. Learning how to clean grout properly once means the weekly scrub stays quick.
Grout cleaning questions
What is the best homemade grout cleaner?
A paste of bicarbonate of soda and water, sprayed with white vinegar and left for five to ten minutes, works well on most grout. Scrub along the lines with a stiff brush, then rinse and dry.
Can you make grey grout white again?
Often, yes. Most grey grout is just dirty, and a bicarbonate paste with a stiff brush brings back much of the original colour. If it stays grey after a good clean, a grout pen or regrouting is the next step.
How do I get black mould out of grout?
Light mould usually lifts with white vinegar and a stiff brush. If it has grown deep into the grout or into the silicone, cleaning only lightens it, and the silicone or grout needs replacing.
Can I use vinegar on all grout?
It is fine on grout between ceramic and porcelain tiles. Avoid it on natural stone such as marble, limestone and travertine, as the acid damages the surface.
How often should I clean grout?
A quick scrub once a week keeps grout from discolouring. A deeper clean with a bicarbonate paste every month or two is enough for most bathrooms.
