Limescale on taps, shower heads and kettles: causes and cleaning

Limescale is the hard, chalky white deposit that builds up in kettles, round taps and in shower heads. It is not dirt. It comes from minerals dissolved in the water, and in much of the UK it is just part of living with the local supply. You can keep it under control with regular cleaning. Understanding where it comes from helps you decide whether cleaning is enough or whether to look at a bigger fix.

Where limescale comes from

The Drinking Water Inspectorate (DWI) explains that water hardness is caused by dissolved calcium and magnesium, and that it varies with local geology. When hard water is heated or left to evaporate, some of those minerals come out as scale.

DWI lists the effects:

• scaling in hot water systems, kettles, electric irons and domestic appliances;
• less lather from soap, washing-up liquid and washing powders;
• tide marks on basins, sinks, baths and toilets;
• a scum on hot drinks, especially tea.

On heating elements, DWI says scaling shortens their life and makes appliances less efficient. That applies to kettles, washing machines, dishwashers, electric showers and immersion heaters.

DWI's page has a map of typical hardness in England and Wales. It says to ask your water company for an accurate figure for your address. Our guide to water quality and hard water areas covers what else you can ask your supplier.

Shower heads

A scaled-up shower head gives a weak, uneven or spitting spray, even when the supply is fine. Clean the head before you blame the pump or the pressure. Our low water pressure guide covers the bigger picture.

1. Rub the nozzles first. Many heads have soft rubber nozzles. Rubbing them with your thumb while the water runs breaks off a lot of scale.
2. Take the head off. Most handsets unscrew from the hose by hand. Some fixed heads come apart. Check the maker's instructions.
3. Soak it. Use a descaler made for the job, following the label. Many people use white vinegar instead. Check the maker's care advice first: some plated, coloured or brushed finishes can be damaged by acids, and some makers say to soak only the nozzle plate.
4. Brush and rinse. Use an old toothbrush, then rinse thoroughly with clean water before refitting.
5. Check the hose washer when you refit. A missing or squashed washer will drip.

On an electric shower, only clean the head and hose. Do not open the shower unit. Anything inside is electrical. See electric vs mixer showers.

Tap aerators

Most modern taps have an aerator, a small mesh insert in the spout. Scale and grit clog it and make the flow splutter.

1. Unscrew the aerator from the end of the spout. Many come off by hand. Some need a special aerator key, usually supplied with the tap.
2. Note the order of any washers and meshes.
3. Soak the parts in descaler or vinegar, brush them and rinse them.
4. Refit them in the same order.

If a tap still drips after cleaning, scale on the seat or a worn washer or cartridge may be the cause. See dripping taps and mixer and bath taps.

Kettles, toilets and glass

• Kettles: use a kettle descaler following its instructions, then boil and discard fresh water once or twice before using it again.
• Toilets: scale builds up under the rim and at the water line. Use a product sold for toilet limescale and follow its label. Do not mix cleaning products.
• Shower screens and tiles: wiping them down after a shower stops scale building up.

Always ventilate the room, wear gloves and keep descalers away from children. Never mix a descaler with bleach.

Heating elements and appliances

Scale also builds up on the parts you cannot see:

• Immersion heaters: scale on the element can affect performance over time. Replacing an element is electrical work. See hot water cylinders and immersion heaters.
• Washing machines and dishwashers: follow the maker's advice on descaling programmes and, for dishwashers, the salt and rinse aid settings. A boiling water tap needs its filter changed as the maker says.
• Electric showers: a shower that runs cooler or keeps cutting out can have several causes. Get a qualified electrician or the shower maker's engineer to look at it.

When scale is a sign of something bigger

If every kettle, tap and shower head in the house scales up fast, the cause is your water supply, not any one fitting. You have three broad options:

• Keep cleaning. For many homes, regular cleaning is enough.
• A water softener treats water for the whole house or part of it. It is plumbing work on the rising main, and you should keep an unsoftened drinking tap. See our water softeners guide.
• In-line scale "conditioners" or inhibitors fitted on a single pipe. Be cautious with these. DWI says magnetic devices "do not soften the water". It notes they were designed originally for large industrial systems with continuous flow, not homes where water often does not flow for hours at night. DWI recommends buying one only on a sale-or-return basis, and asking for performance data in a home setting.

Products at Wickes

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

Is limescale harmful to drink?

DWI notes that there are no UK drinking water standards for hardness, calcium or magnesium. Limescale is mainly a nuisance for appliances and cleaning. If you are worried about your water, ask your water company for its water quality report.

Why does my shower head scale up so fast?

Hot water, small nozzles and evaporation between showers all help scale form. In a hard water area, regular cleaning or a head with rub-clean nozzles makes it easier to manage.

Do magnetic scale reducers work?

DWI says magnetic devices do not soften the water. It recommends buying one only on a sale-or-return basis, and asking for evidence of how it performs in a home.