Tile and Grout Cleaning Guide: Why Grout Darkens and What Helps

Why does grout get darker over time?

Because grout is porous and tiles mostly aren’t. Most grout is a cement-based mix with a slightly rough, open surface. Tiles shed dirt easily, but grout soaks it up and holds on to it.

The grout lines also sit a little lower than the tile surface. Dirt, water and grease naturally run into those low channels and settle there. Over months and years the colour of the grout changes, even when the tiles themselves look fine.

The main causes

• Mop water. This is the big one. A mop lifts dirt from the tile, then the dirty water runs into the grout lines and dries there. Each mop leaves a little more behind.
• Kitchen grease. Cooking oils settle on kitchen floors and act like glue for dust and grit.
• Soap and body products. In bathrooms, soap residue and hair products build up along the grout, especially around showers.
• Grit from shoes. Entranceways and hallways collect fine soil that gets ground into the lines.
• Spills. Coffee, juice, wine and sauces soak into grout quickly if they’re not wiped up.
• Damp. In bathrooms and laundries that don’t air out well, grout can stay damp and discolour.

Why doesn’t normal mopping fix it?

Mopping is good for the tile surface, and it’s worth doing. But it isn’t designed to pull soil out of the grout. As mentioned above, it often moves dirt into the grout instead.

Scrubbing harder with a brush can help a little, but the dirty water and loosened soil still end up sitting in the lines unless they’re removed. That’s the step a home clean usually misses.

What does a professional tile and grout clean do?

The difference is that the dirt is rinsed out and taken away, not spread around. In general terms, a professional clean:

1. Checks the floor first, looking at the tile type, the grout condition and any problem areas, and whether it’s natural stone, which needs different care.
2. Applies a professional tile and grout cleaner to loosen built-up grime and grease.
3. Agitates the grout lines so the cleaner can work into the pores of the grout.
4. Rinses with hot water and extracts the dirty water straight away, so it isn’t left to dry back into the lines.

The details of how I do this are on my tile, grout and vinyl cleaning page. Grout colour can often be lifted a long way. Results vary with how old the grout is, what’s in it and whether it has been stained right through.

What is grout sealing?

Here’s some general information, as sealing is something people often ask about. A grout sealer is a liquid that soaks into the grout and makes it less absorbent. It doesn’t make grout waterproof or stain-proof, but it slows down how quickly dirt and spills soak in, and it can make everyday cleaning easier.

A few basics worth knowing:

• Clean first. A sealer locks in whatever is in the grout. Sealing over dirty grout seals the dirt in.
• Dry first. Sealers generally need clean, dry grout to soak in properly, so follow the product’s instructions on drying before and after.
• It wears off. Sealers don’t last forever, especially in busy kitchens and showers. Product instructions usually say how to check and when to reapply.
• Match the product to the surface. Some tiles, particularly natural stone, need a specific type of sealer. Check with the tile supplier or the product maker.
• Some grout doesn’t need it. Epoxy grouts are much less porous than cement grout. If you’re not sure what you have, the person who laid the floor may know.

What can’t tile and grout cleaning fix?

Cleaning removes dirt. It can’t repair the grout or tiles themselves. Be realistic about these:

• Cracked grout. Cracks let water and dirt in underneath. They need repair, not cleaning.
• Missing or crumbling grout. If grout is washing out or gaps have appeared, it needs regrouting.
• Permanent staining. Some dyes, rust and old spills soak right through the grout. They can often be lightened but may not go back to the original colour.
• Chipped or cracked tiles. Cleaning won’t hide damage to the tile itself.
• Etched or dull stone. Acidic spills and the wrong cleaners can dull natural stone. That’s surface damage, not dirt.
• Mould inside the grout or behind tiles. If a bathroom keeps getting damp and discoloured, there may be a ventilation or water problem that needs looking at first.

If I see any of these, I’ll tell you up front rather than leave you expecting new-looking grout.

How can I look after tiles and grout between cleans?

Simple habits make the biggest difference. This is first aid and everyday care, not a deep clean:

• Sweep or vacuum before you mop, so you’re not turning grit into muddy water.
• Change your mop water often. Once it looks grey, it’s putting dirt back down.
• Wring the mop well. Less water on the floor means less running into the grout.
• Wipe spills straight away, blotting rather than smearing.
• Let bathrooms air out. Open a window or run the extractor fan after showers.
• Use mats at entrances and in front of the kitchen bench.
• Avoid harsh acids, bleach and abrasive powders. They can damage grout, wear down sealers and etch natural stone, making things worse over time.
• Don’t mix cleaning products. Some combinations are dangerous.

If the grout is still dark after normal cleaning, send me a few photos and I’ll tell you honestly what a clean is likely to achieve.

Can tiles be done at the same time as carpets?

Yes. Tile and grout cleaning can be booked with a carpet clean, so the kitchen, bathroom and hallway tiles are done in the same visit as the bedrooms and lounge. That’s handy at the end of a tenancy. For carpets, see hot water extraction carpet cleaning.