Limescale is the most common “plumbing fault” I get called out for that turns out to be nothing of the sort. A showerhead that’s gone weak and spitty, spraying sideways at the screen instead of straight down, has almost always just furred up with chalk. London sits on an enormous seam of the stuff.
The job is the same underneath whether it’s a Victorian conversion or a glass-box new-build. What changes is how far people let it go before they ring anyone.
Why does limescale build up so fast on a London showerhead?
Most of London’s tap water comes from the Thames and the Lee, and both run over chalk and clay long before Thames Water gets near them. That water arrives hard. Properly hard. Every time it dries on a warm metal surface it leaves behind a thin crust of calcium carbonate, and a showerhead is about the warmest and most-used bit of metal in the flat.
The nozzles are the problem. On a modern head those little rubber jets are only a millimetre or two across, so it takes almost nothing to block one. Six months of a family of four showering twice a day and half of them are furred shut.
Warm water drops its calcium faster than cold, which is why the head furs up while the cold tap two feet away stays clear for years. The hotter you run the shower, the quicker the crust builds.
You notice it first as a spray that fans out wrong. One jet going rogue, hitting the tiles. Then two.
Is it worse in some London boroughs than others?
People love to tell me their corner of London has the worst water. Someone in Bexleyheath will swear blind it’s harder there than anywhere else in the city. It mostly isn’t true. The supply across the Thames Water area runs fairly consistent, and it’s all hard – whether you’re in Zone 1 or out past the North Circular, you’re getting chalk. I’ve taken test strips to jobs in Enfield and in Wandsworth on the same week and got readings close enough that it made no odds to the advice. The difference you feel between one flat and the next has more to do with how hot the household runs the shower and how long water sits in an old head than with the postcode on the door.
What works for descaling – and what’s a waste of money?
White vinegar. That’s the whole answer for most heads, and it costs about 40p.
The acetic acid in ordinary white vinegar dissolves calcium carbonate, slowly but completely, and it won’t touch the chrome or the rubber nozzles while it does. Citric acid powder works too, a touch faster, but for a single showerhead the difference is academic.
This is the bit people argue with me about. The proprietary limescale sprays and “showerhead descaler” sachets that cost four or five quid a go are, nine times out of ten, doing exactly what the vinegar does and charging you for a nice bottle and a scent. I once watched a homeowner in Muswell Hill work through a whole cupboard of branded gunk on a head that a jam jar of vinegar cleared overnight. Buy the vinegar.
The one thing I’d steer you off entirely is anything abrasive. No wire wool, no scouring pad on the finish, no cocktail stick jammed into every nozzle in a temper. You’ll scratch the plating and score the rubber, and a scored nozzle scales up faster next time.
Vinegar or citric acid – does it matter which?
For a chrome-plated head, either is fine. If yours is aluminium or has any bare, unlacquered metal – some of the old brass fittings in period conversions do – I’d lean towards citric acid at a mild dilution and keep the soak short, because strong vinegar left on bare metal for hours can dull it. For the chrome-and-plastic thing screwed to most London showers, use vinegar, neat, overnight. Done.
How do you descale a showerhead you can’t unscrew?
This is the situation I get most, and it’s where the good trick lives.
Half the heads in London flats won’t come off. Nine times out of ten they’re seized solid with – you guessed it – limescale in the thread, or they’re a fixed head plumbed into the wall with no join you can reach. You don’t need to remove anything.
Half-fill a strong sandwich bag with vinegar and pull it up over the whole head so the nozzles are submerged. Hold it there with an elastic band or a hair bobble round the neck of the fitting. Leave it overnight. In the morning the crust has gone soft, so you slip the bag off and run the shower hot for thirty seconds to blow the loosened scale out through the jets. Wipe the face with a cloth.
If you’re impatient, warm the vinegar first, just off the kettle and left to stand a minute so it isn’t boiling, and the soak that would take a night is done in an hour or two. Run the shower before you start, as well, so you know what you’re comparing against. A head you’d swear was fine will often have three or four dead jets you’d stopped clocking, and the pressure jumps back the second they clear.
One soak clears the vast majority. If a couple of jets are still stubborn afterwards, a second overnight bag will get them – a lot kinder than poking at them with anything hard. The vinegar smell hangs about for a shower or two and then goes.
I did this in a rented flat on the Isle of Dogs last winter – one of the towers off Marsh Wall, tenant moving out, fixed rainfall head she’d never once cleaned in three years. The bag was brown by morning. The head went from six working jets to the full grid, and she got her deposit back on the bathroom.
If the thread has seized and you want the head off for a deeper clean, bag it first to let the vinegar work the scale in the joint loose, and it’ll usually turn by hand after.
What if it’s a big fixed rainfall head?
Same method, bigger bag. A wide rainfall head is a nuisance because a sandwich bag won’t reach round it, so I use a bin liner and more vinegar, and I tape the top up rather than fight an elastic band that won’t stretch that far. The face of those big heads is usually a silicone mat of nozzles you can rub with a thumb once it’s soaked, and most of the softened scale rolls straight off under your finger. Gentle, though. It’s silicone, not stone.
How often does a London showerhead need descaling?
This next one gets people going. Most are told to descale monthly, and for most London flats monthly is overkill bordering on a chore invented to sell products.
For an ordinary household – a couple, or one or two people, showering normally – every three months keeps a head clear with no drama. A busy family bathroom with the shower running six or eight times a day is more like every six weeks, because the sheer volume of hard water through the jets furs them faster. A guest bathroom nobody uses? Twice a year and you’ll never notice a problem.
The spray tells you more than any calendar does. Nine times out of ten it’s one jet fanning sideways that flags it, weeks before the whole head gives up. Do it then. There’s no sense running a monthly schedule on a head that’s perfectly clear – that’s just moving vinegar around for the sake of it.
There’s a knock-on worth knowing too. The same hard water blocking the head is furring up the element in an electric shower and the plates in a combi boiler, and those you can’t sort with a bag of vinegar. The visible scale on the head is a rough gauge of what’s happening in the bits you can’t see. I pulled an electric shower off a wall in Streatham last year that had scaled its element half solid – the spitty head was the least of that tenant’s problems.
Does a water softener change the answer?
If the flat has a softener plumbed in – rare in rentals, more common in owned houses out towards Bromley and the Surrey edge – then yes, completely. Softened water barely scales at all, and you can more or less forget the showerhead for a year at a stretch. Most London flats don’t have one, and I wouldn’t tell a tenant to fit one purely for the shower. The point-of-use filters that screw between the hose and the head help a little and clog themselves in the process, so you’ve swapped descaling the head for replacing a cartridge. Swings and roundabouts.
Will descaling ruin the chrome or the finish?
Not if you use vinegar or citric acid and keep the scrubbing off it.
Chrome plating shrugs off a mild acid soak. So does the moulded plastic that most heads are made from under the shiny coating. The trouble starts with the wrong tool or the wrong finish, and matte black is the one to watch.
What about matte black and brushed finishes?
Matte black and brushed-nickel heads have got popular in the smarter new-builds all over places like Nine Elms, and they mark more easily than plain chrome. The finish is thinner and the matte texture shows every water spot. Acid won’t strip it, but a rough cloth will burnish shiny patches into the matte, and once that happens there’s no undoing it. Rinse it and pat it dry with a soft microfibre. Never rub a dry matte head hard to “polish” it – you’ll polish it whether you meant to or not.
The rubber nozzle tips are the last thing worth a word. On most heads they’re little raised silicone nibs, and the reason they exist is that you can rub scale straight off them with a fingertip or a soft toothbrush after a soak. Do that every few weeks and the head barely scales at all.
Leave a bag of vinegar on the head tonight and check it in the morning.