Removing Stains From Floor Tiles and Grout in Delhi

Why does grout go black or yellow?

Four different causes, and they look similar from standing height. Get down and look closely, because the fix depends entirely on which one it is.

• Ground-in dirt and dust. Uniform grey-brown darkening across a whole floor, worst in walking paths. This is the ordinary Delhi case and it usually cleans up well.
• Mould and mildew. Black or dark green speckling, concentrated in the shower corner, along the bathroom skirting, behind the WC and under the kitchen sink. It has a musty smell and it comes back quickly if the area stays damp.
• Hard water and soap scum. A pale, chalky yellow-white crust along the grout, often with a dull film on the surrounding tile. This is limescale plus soap, and it needs dissolving rather than scrubbing.
• Permanent staining or worn grout. Grout that has eroded below the tile edge, gone powdery, or been dyed by something like haldi, tea, rust or paint. Cleaning improves the look slightly and then stops working.

One useful test: wet the grout line with plain water and look at it while wet. If it looks close to its original colour when wet, the discolouration is largely surface dirt and cleaning will work. If it stays dark when wet, the colour has soaked into the grout, and you are heading towards recolouring or regrouting.

What actually cleans grout?

A stiff narrow brush and dwell time. The brush matters more than the product — grout is a recessed line, and a flat mop simply passes over it without ever touching the bottom of the groove.

• Get a grout brush or an old toothbrush. Narrow, stiff bristles that reach into the line. This one change fixes most complaints that "nothing works".
• For ordinary dirt: baking soda paste. Mix baking soda with a little water into a paste, work it into the lines, leave it ten minutes, scrub along the line, rinse. Cheap, safe on almost everything and surprisingly effective.
• For mould in a bathroom: dilute bleach or a mould remover, on tile only. Apply to the affected lines, leave it for the time on the label, scrub and rinse thoroughly. Ventilate the room, wear gloves, and keep it off any adjoining natural stone or metal.
• For hard water crust: a mild acid, again on tile only. Diluted white vinegar or a bathroom limescale remover left to dwell, then scrubbed. Rinse fully, because acid left on cement grout weakens it over time.
• Work in small sections and rinse each one. Dirty rinse water spread across a floor redeposits everything you just lifted.
• Never mix bleach and an acidic cleaner. Together they release a toxic gas. Do the bleach work, rinse thoroughly, and use the acid on a different day if you need both.

The grout keeps going black again. What am I missing?

You are cleaning the mould but not removing the damp that feeds it. Mould needs moisture; take the moisture away and the problem largely takes care of itself, especially through a Delhi monsoon.

• Ventilate after every bath. An exhaust fan running for a while after showering, or a window open, is the difference between a bathroom that dries in an hour and one that never dries at all.
• Squeegee or wipe the wet areas. Pushing standing water off tiles and out of corners after a shower removes most of what mould lives on.
• Check for a real leak behind the wall. Grout that goes black in one specific patch and nowhere else, especially near a WC, a shower valve or a shared wall, often means water is arriving from behind rather than from the room. Cleaning it forever is pointless.
• Look up as well as down. Dark patches on a ceiling or the top of a wall usually mean seepage from a bathroom above or from the terrace, which is a waterproofing question, not a cleaning one. Our wall seepage and waterproofing page covers that.
• Fix a slow-draining floor trap. Water that pools instead of draining keeps the grout permanently wet.

If the room genuinely dries out between uses and the mould still returns within days, treat that as evidence of a moisture source rather than a cleaning failure.

Should I seal the grout, and does it work?

Sealing is worth doing on cement grout in wet areas, with realistic expectations. A grout sealer soaks into the porous cement and makes it repel water and dirt for a while, so spills sit on top long enough to be wiped instead of soaking in.

• Seal after cleaning, never before. Sealing over dirty grout locks the stain in permanently. The grout must be clean and completely dry first, which usually means waiting a day.
• It wears off. A sealer is not permanent, particularly in a shower or a kitchen that is washed daily. Expect to redo it periodically, and take the water-beading test as the signal — when water stops beading and soaks straight in, the sealer has gone.
• It reduces staining, not mould. If the wall stays wet, mould will still grow on the surface. Sealing helps it wipe off more easily; it does not prevent it.
• Epoxy grout is a different product. It is non-porous by nature, does not need sealing and resists staining far better than cement grout. It is worth asking about when tiles are being laid or a bathroom is being redone, rather than something you switch to later.
• Grout recolouring exists. A grout colourant or pen coats the line and restores an even colour on grout that is sound but permanently stained. It is cosmetic and it wears, but it is far less work than regrouting.

When is it time to regrout instead of clean?

When the grout has failed physically rather than just looking bad. Cleaning cannot rebuild missing cement, and continuing to scrub damaged grout makes it worse.

• The grout is crumbling or powdery. If it comes away when you scrape it with a coin, it has lost its bond and water is getting behind the tile.
• The line has sunk well below the tile face. Erosion means less cement, more trapped dirt and a groove that will never look clean.
• There are cracks, or a tile sounds hollow when tapped. That points at movement or water underneath, and it needs looking at before it spreads.
• It stays dark when wet. The stain is in the material. Recolouring or replacement, not cleaning.
• The silicone at wall-to-floor and around the sink is black. That is silicone, not grout, and it cannot be cleaned back once mould is inside it. It is cut out and replaced — a small job that transforms how a bathroom looks.

Before booking anyone, do one test patch yourself in a hidden corner. It takes twenty minutes and tells you whether you have a cleaning problem or a repair problem, which is exactly what you want to know before someone quotes you. A full grout clean across a bathroom is usually handled as part of bathroom deep cleaning, and kitchen floors and backsplashes are covered in kitchen deep cleaning. Ask any cleaner what they intend to use in the bathroom, and tell them if any surface in the house is natural stone.