How to remove limescale from taps, showers, toilets and kettles

Limescale is removed with acid, but not every surface can withstand it. On ceramics, glass and toilets you can use an acidic descaler or a citric acid solution according to the label; on taps and showers use only what their manufacturer permits; and acids do not belong on marble and limestone at all. The most effective prevention is to dry surfaces after use.

How hard is the water in Prague

Limescale consists mainly of calcium and magnesium carbonates, which are deposited from water during heating and evaporation. The harder the water, the faster it builds up. In its answers to questions about water quality, Pražské vodovody a kanalizace (Prague Water Supply and Sewerage) states that drinking water in Prague is mostly soft to moderately hard, depending on where it comes from. According to PVK, water from the Káraný treatment plant is harder than water from Želivka and supplies mainly the north of the city.

You can find the exact figure for your address in the Water Quality Map, to which PVK links from the same page; hardness is given there in mmol/l. It is also worth knowing for setting up your dishwasher or washing machine, which take water hardness into account.

What to use to remove limescale

Acids work on limescale. In its overview of commercial products, the Toxikologické informační středisko (Toxicology Information Centre, TIS) states that descalers contain various acids, mainly weak organic ones such as acetic and citric acid, and that depending on concentration they may irritate mucous membranes. According to TIS, toilet and sanitaryware products contain sodium hypochlorite or acids.

• citric acid dissolved in water, or a ready-made descaler based on it,
• vinegar, which, however, manufacturers consider unsuitable for taps (see below),
• acidic bathroom and toilet cleaners, always according to the label,
• soft cotton cloths, a sponge without an abrasive side, and an old toothbrush for grout and around the aerator,
• gloves and an open window.

The usual rules for any chemicals apply: read the label, ventilate, wear gloves, test first on a small inconspicuous spot, and never mix products containing chlorine with acids or with ammonia. For toilet products, TIS explicitly warns that they must not be mixed, as chlorine gas may be released. The article on dangerous combinations of cleaning products explains this in more detail.

Taps and showers: follow the manufacturer

Chrome taps and shower heads are more sensitive to acids than they might seem, and manufacturers' recommendations differ. So first find out the brand and look up its instructions.

In its cleaning and maintenance section, Hansgrohe recommends a mild citric-acid-based cleaner and advises against cleaners containing hydrochloric, formic or acetic acid, as well as chlorine bleach, because they can seriously damage the products. The manufacturer's procedure:

1. Do not spray the cleaner directly onto the tap, but onto a cotton cloth.
2. Observe the dosage on the label and leave it to work for no more than 10 minutes.
3. Rinse thoroughly with clean water.
4. Do not use abrasive powders or rough sponges.

GROHE is stricter. In its care instructions, it advises against abrasive sponges and cleaners containing solvents, acids, descalers, vinegar or acetic acid products. It recommends cleaning with a little soap and a damp cloth, rinsing and drying with a soft cloth; for limescale it refers to its own cleaning product. If you have a tap of another brand, look for its manufacturer's instructions and, if in doubt, choose the gentler method.

Shower head and aerator

Limescale in the shower nozzles reduces and scatters the water jet. Some shower heads have flexible nozzles from which, according to the manufacturer's instructions, limescale can be loosened by rubbing with your fingers; check what the instructions for yours say. The aerator, i.e. the small strainer at the end of the spout, can be unscrewed on many taps and descaled separately in a solution permitted by the tap's manufacturer. Hansgrohe states that only the metal shower disc, not plastic parts, is suitable for the dishwasher.

Washbasin, bath, glass and tiles

Acidic descalers are commonly used on ceramics, enamelled baths, shower enclosure glass and glazed tiles. Always read which surfaces the product is intended for, as well as the sanitaryware manufacturer's instructions.

1. First wash the surface with an ordinary cleaner so that the acid acts directly on the limescale.
2. Apply the descaler according to the label; on vertical surfaces, ideally on a cloth or as a gel.
3. Leave it for the prescribed time, no longer.
4. Wipe off, rinse thoroughly with clean water and dry.

Protect the grout between tiles: do not leave an acidic product on it for longer than the label states, and always rinse it well after cleaning. You will find the complete procedure for the shower in the article how to clean a shower enclosure.

Marble and natural stone: avoid acids

Marble, limestone and travertine consist mainly of calcium carbonate, a substance similar to limescale itself. In its natural stone care recommendations, the Natural Stone Institute states that calcium carbonate is sensitive to acidic solutions, and products containing lemon, vinegar or other acids can dull or etch such stone. It recommends a neutral cleaner, stone soap or a mild washing-up liquid with warm water, thorough rinsing and drying with a soft cloth. In a shower with stone cladding, it advises wiping the water off with a squeegee after each use.

Toilets and electric kettles

In a toilet bowl, limescale tends to be heaviest under the rim and at the standing water level. Use a toilet cleaner according to the label, leave it to work and then scrub with a toilet brush. Never use an acidic cleaner and a chlorine product one after another without flushing thoroughly, and never mix them; TIS explicitly warns of the risk of chlorine being released with these products.

Descale a kettle with a product designed for kettles or a citric acid solution according to the kettle manufacturer's instructions. After descaling, fill it with clean water several times, boil it and pour the water away so that no residues remain. Do not drink the descaler and keep it out of the reach of children; if swallowed, TIS advises not inducing vomiting. For washing machines and dishwashers, follow the manufacturer's instructions; the articles how to clean a washing machine and how to clean a dishwasher describe the procedure.

Overview by surface

The table summarises the recommendations from the sources cited in the article. The specific instructions of the manufacturer of your surface or appliance always take precedence.

Prevention: less limescale, less work

• Dry after use. GROHE states that drying the tap after each use is the simplest way to prevent limescale build-up.
• A squeegee in the shower. A few strokes after showering will save you cleaning the glass and tiles.
• Regularity. A thin layer can be removed with a gentle product in a few minutes; a thick one only by repeated cleaning.
• Appliance settings. Set the water hardness from the Water Quality Map in your dishwasher and other appliances that allow it.