# How to descale a kettle with citric acid

Citric acid is a cheap, food-safe, odourless way to dissolve the limescale (calcium carbonate) that builds up in kettles in hard-water areas. It works faster than vinegar and leaves no smell or taste behind.

## What you need

- Citric acid powder (food grade)
- Water
- A soft brush or non-scratch sponge (optional)
- A cloth for drying the outside

## Amounts

| Kettle size | Water | Citric acid |
| --- | --- | --- |
| Small (up to 1 litre) | 500 ml | 1 tablespoon (about 15 g) |
| Standard (1.5–1.7 litres) | 1 litre | 2 tablespoons (about 30 g) |
| Heavy scale, any size | Fill to the minimum line plus a little more | Increase to 3 tablespoons (about 45 g) per litre |

As a rule of thumb, use roughly **30 g of citric acid per litre of water**. Always use at least enough water to cover the element or the heated base plate and to reach the kettle's MIN line.

## Method

1. **Empty the kettle** and rinse out any loose flakes of scale.
2. **Add the water** (see amounts above), making sure it is above the MIN line.
3. **Boil the water** once, then switch the kettle off.
4. **Add the citric acid** to the hot water. Add it slowly: it will fizz as it reacts with the scale, and adding it to boiling water all at once can make it foam over.
5. **Leave it to soak for 15–20 minutes.** For heavy scale, leave it for up to 1 hour, or reboil once and soak again.
6. **Pour the solution away** down the sink. It is harmless to drains and will help clean them.
7. **Scrub any remaining spots** gently with a soft brush or sponge. Never use metal scourers on the element or the inside of a stainless-steel kettle.
8. **Rinse thoroughly.** Fill the kettle with clean water, boil it and pour it away. **Do this two or three times** so no citric acid remains.
9. **Wipe and dry** the outside of the kettle.

## How often to do it

| Water hardness | How often |
| --- | --- |
| Hard water (much of London, the South and East of England) | Every 2–4 weeks |
| Moderately hard water | Every 1–2 months |
| Soft water | Every 3–6 months, or when you see scale |

Descale sooner if you notice white flakes in drinks, a chalky film inside the kettle, a louder or slower boil, or the kettle switching off early. Regular descaling keeps the kettle efficient: scale insulates the element, so a scaled kettle uses more energy and takes longer to boil.

You can also descale the kettle's **filter** (usually behind the spout) by soaking it separately in a small bowl of the same warm solution for 15 minutes.

## Safety notes

- **Unplug the kettle** before handling the base, the element or the filter, and keep the base and electrical contacts dry.
- **Watch out for foaming.** Adding citric acid to very hot water can make it fizz up suddenly. Add it gradually and never fill the kettle above the MAX line.
- **Do not reboil an unattended kettle** while it contains the solution; foam can reach the lid and the switch.
- **Handle hot water carefully** when pouring the solution away. Let it cool for a few minutes if you prefer.
- **Rinse well before using the kettle for drinks.** Citric acid is food safe, but leftover solution will taste sour.
- **Keep citric acid powder away from your eyes.** It is an irritant; if it gets in your eyes, rinse with plenty of clean water. Store it out of reach of children.
- **Don't mix it with other cleaners**, especially bleach or other chemical descalers.
- **Check the manufacturer's instructions first.** Some kettles (for example ones with special coatings, or some aluminium kettles) may not be suitable for acid descaling. Never put a kettle base or a corded kettle in water.