DIY remedies to get rid of dirty bathroom grout

Don’t just pout about grubby old grout – get rid with our simple DIY guide

Dirty grout around water outlets is a perennial problem that will spoil the look of any pale to grey grouting.

There’s nothing that mucks up the looks of your bathroom, old or new, like dirty, mouldy or discoloured grout. 

It’s a creeping problem that can defeat even the best mechanical ventilation if not addressed. Degrading grout is not something to ignore as that classic mixture of water, cement and sand is part of the overall waterproofing of your bathroom, especially around showers and basins. 

There’s a temptation when we notice the problem on pale or white grout, to swing out the bleach bottle and hit it in an undiluted attack. The trouble is that bleach and ammonia mixtures are caustic, corrosive and reactive. It can eat away at the composition of grout causing it to become chalky and crumble over time, even if you do get the grot off. 

Even worse, it bleaches mould and mildew, but it does not kill it, and it’s not good for the metal components you may hit in your enthusiasm too (see speckled damage on your chrome taps – chances are that’s self-inflicted over use of bleach-based cleaners). So, start easy with something that won’t eat a hole in your hand.

Home-made solutions

CLIMATE & SUSTAINABILITY HUB

Make up a paste with bicarbonate of soda and water, forming a malleable paste that won’t drip straight off the wall. Smother the grout with the paste, working it onto the grout lines with an old soft/medium grade tooth-brush. Go and have a cuppa, taking a good 20 minutes to half an hour. Test an area by wiping off a small portion and see if the cleaning action has started before wiping and rinsing off your paste.

There are influencers advocating for white vinegar or even white wine vinegar, but this is a mistake, as the acid in the vinegar can sit on unsealed grout and again, cause it to decay – this is one place not to deploy the magic of green cleaning with white vinegar. If any vinegar is smeared on natural stone tiling – it can cause further damage, and mixed into bleach it can release toxic chlorine gas.

Commercial products

Going to a safe, commercial product, HG Grout Cleaner (around €6.50 for 0.5l) is a reputable, popular solution. So, say after all this effort, you are left with areas of grout that are collapsing or remain discoloured. There are two solutions. 

First of all, if it’s just discolouration, you can apply a coat of new colour with a water-based, non-toxic grout pen. Now, grout pens come in a range of colours through white, grey and beige, and it’s vital to match the colour as closely to the original colour if you’re not doing the entire tiled area. 

There’s a chance here to change the colour if you like, although white may need several applications over a darker original. Practise before you start, as grout pens can bleed onto the tile, and avoid using them on lines of grouting to an almost rectified (edge to edge) tile, as the finish will be messy.

Grout pens are useful for small areas if you find the staining just will not shift. Quality pens should not fray before the ink runs out. Unibond Grout Reviver from 12, woodies.ie.

Shake the pen well before starting. Pressing the pen down with as consistent pressure as you can manage will deploy a pump mechanism – it should not drip when you’re touching up walls. 

The most successful application for grout pens are white grout and gloss white tile with a good groove to grab and guide the pen. Better brands promise that the pen tip will not fray before the paint runs out.

Grout-ripping

So, what if the grout is shot, and you don’t want to replace the tile? Then the grout really has to come out and be replaced, a job with the terrifying title of grout-ripping. 

Now, done carefully, you could rake out your own grout, but don’t start wildly gouging at it with a flat head screwdriver. It can be done with a simple hooked or saw-edged little hand tool with a carbide alloy head, or using a small power tool with a bit of pneumatic action to break up the old materials. 

Old style grout-ripping is a tedious job that tilers dread – so break it up into a few sessions to save your sanity. For this and any grout removal, stick on some safety glasses as small pieces of material can fly in any direction.

With a small electrical dedicated grout removing device (they start in the € 25 range, but trust me, it’s worth the money for a larger project up to say 5m2 - 10m2) you are good for 2mm to 3mm grout lines. 

There’s usually just one blade provided with an entry level grout remover. The sensation while running the grout lines is rather like holding an electric toothbrush at a 45 degree angle - a little tiring on the hand and wrist, but grout removers take the dread out of dealing with endless dirty metres.

Taking your time, and handled with care, it should leave your tile edges undamaged, but I would be wary of any glass tile or mosaic – because, well, it’s glass. 

Most drills and some multi-tool platforms offer a dedicated grout removal blade – these are best used by a relatively competent hand as the machine is that bit heavier and if you stutter, you could damage the tile. Slot the blade edge well into the grout line and use that consistent pressure we talked about for a clean cut.

Occasional areas of really tough cement-like grout can be left in place and grouted over, but otherwise, aim to take out all the loose material after you’ve passed through it. Going too deep, there is the potential to cut into waterproof tanking materials holding the water off the supporting wall or floor. 

Don’t get out of your league to save a moderate amount of money – that’s what skilled trades are there for. Going on to re-grouting, they are likely to do a much better job than you ever could, and a tiler can also replace the odd cracked tile if you were clever enough to keep spares from the install.