How to Remove Limescale from Taps and Showerheads

Why Limescale Comes Back So Quickly

If you live in a hard water area — much of London, the South East, East Anglia and the Midlands — you already know the routine. You scrub the tap spout clean, and a fortnight later there is that familiar chalky crust again. That crust is limescale, mostly calcium carbonate, left behind when water evaporates and deposits the dissolved minerals it was carrying. London tap water can carry over 250mg of calcium carbonate per litre, which is why scale appears fast on anything that gets regularly wet and dried: tap spouts, aerators, showerheads, shower screens and the base of the shower tray.

The good news is that limescale is alkaline, so acid dissolves it. You will see the tell-tale fizzing as the acid reacts and turns the carbonate into soluble salts and carbon dioxide. The skill is choosing an acid that is strong enough to shift the scale without damaging the metal, plastic or stone it has attached itself to.

The Specialist Chemicals Worth Keeping Under the Sink

Most proprietary descalers are built around one or two of the following. Knowing what is in them helps you pick the right one.

• Citric acid — the gentle all-rounder, usually bought as a powder and mixed with warm water. Around one to two tablespoons per litre is plenty for routine descaling. It is kind to chrome, plastic and rubber, low in odour, and safe to use around the bathroom.
• Acetic acid (white vinegar) — cheap, effective and widely available, but the smell lingers and long soaks can dull or pit chrome and nickel plating. Fine for a quick 20-minute soak on a removable showerhead, less ideal as your everyday answer.
• Sulphamic acid — the active ingredient in many kettle and coffee machine descalers. It works faster than citric acid, has less odour, and is a good choice for heavily scaled stainless steel and plastic showerheads.
• Phosphoric acid — common in bathroom descalers, works quickly on chrome and leaves a bright finish when rinsed thoroughly.
• Chelating cleaners (EDTA-based) — these bind the minerals rather than dissolving them. They are slower, but they are the safe option for natural stone and delicate metal finishes.

Surfaces That Need Careful Handling

Acid is indiscriminate, so protect anything that does not enjoy being dissolved.

• Natural stone — marble, limestone, travertine and slate etch permanently on contact with acid. Use a chelating cleaner instead, and never let vinegar or citric acid spray drift onto a stone splashback or floor.
• Aluminium and zinc — acid attacks these metals directly. Avoid entirely on aluminium window fittings and anodised trims.
• Worn chrome plating — intact plating is fine, but once it is scratched or flaking, acid gets underneath and speeds up the damage. Skip abrasives such as wire wool and scouring pads at all times.
• Rubber washers and seals — prolonged soaking can harden them. Keep soaks short and rinse well.
• Never mix an acidic descaler with chlorine bleach — the combination releases chlorine gas. Rinse the area thoroughly if you have used bleach, and work with the window open, wearing gloves and eye protection.

Descaling a Showerhead Properly

Start by checking whether the head unscrews. Many handheld heads simply twist off, which makes the job far easier. Mix a citric acid solution in a bowl — roughly one tablespoon to 500ml of warm, not boiling, water — and submerge the head for one to two hours. For heavy build-up, leave it overnight. A soft toothbrush will lift the softened residue from the nozzles; a cocktail stick or pin is useful for poking out blocked jets.

For a fixed head, use the bag method. Fill a sturdy freezer bag with the warm solution, slip it over the showerhead so the nozzles are submerged, and secure it with an elastic band around the arm. Leave for an hour, then remove, brush, and run the shower hot for a minute or two to flush the loosened scale through.

Avoid submerging the flexible hose itself — the inner liner does not appreciate acid baths. A wipe with a cloth dampened in the solution is enough to remove surface film.

Taps, Spouts and Aerators

The aerator at the tip of most modern taps unscrews by hand or with a small spanner and is usually the worst offender. Soak it in citric acid for half an hour, rinse, and refit. For the tap body, soak a cloth in the solution, wrap it around the spout, and cover with cling film to stop it drying out. Twenty to thirty minutes is plenty on a plated finish; there is no benefit in leaving it for hours.

Rinse thoroughly with clean water afterwards and buff dry with a microfibre cloth. If your taps have a matte black, brushed brass or powder-coated finish, follow the manufacturer's guidance first — some of these coatings are sensitive to acid and prefer a mild soap and water wipe.

Little Habits That Keep Scale Away

Prevention is far less work than removal. Squeegee the shower screen after every use and give the showerhead a quick wipe, since scale only forms where water is left to evaporate. A weekly once-over with a diluted citric acid spray stops deposits setting hard. If your water is very hard, a whole-house softener or an ion-exchange shower filter will cut scale dramatically and make your cleaning chemicals go much further. Running showers a little cooler also helps, as hot water deposits carbonate faster than warm water does.

Get into the habit of drying taps after use and descaling the kettle and showerhead on a set date every couple of months. Your bathroom will look brighter for it, and the surfaces you are trying to protect will last far longer.