🌿 How to Descale a Kettle and Coffee Maker

Hannah writes: "I'll confess, I've never descaled anything in my life." White flakes in your tea, a coffee maker that gurgles for ages: we've all seen it.

Below: how to clear limescale from a kettle and a drip coffee maker safely, how often, and a summary card to keep.

Hannah's letter

"There are white bits floating in my tea and a crust in the kettle. The coffee machine takes forever and the jug has a chalky ring. Scrubbing hasn't helped. Is this stuff making me ill?" — Hannah, shared flat, three serious tea drinkers

The clue in your letter

Hannah, the line that jumped out was "a chalky ring". Mr. Coffee treats calcium rings on the jug as a sign of hard water, and hard water means faster scale.

The short answer

It isn't harmful, it's chalk. A mild acid dissolves it; a sponge never will.

Limescale is mostly calcium carbonate, left behind when hard water is heated. Which? says it's harmless to drink, but a scaled element takes longer, and uses more energy, to boil.

Descale the kettle

Pick one, both from Which?:

• Citric acid: boil a half-full kettle, switch off and unplug, add one to two tablespoons. Leave 15–20 minutes, pour away, rinse twice.
• White vinegar: equal parts vinegar and water, about three-quarters full. Boil, leave until completely cool, empty and rinse.

Then boil fresh water and tip it away two or three times. At the café, citric acid does the kettles; nobody wants a vinegar flat white.

Descale the drip coffee maker

1. Empty the jug and the filter basket.
2. Fill the reservoir with roughly one part white vinegar to two parts water, or your manual's mix.
3. Use the clean setting, or brew a full pot.
4. Leave it 15–30 minutes, then pour away.
5. Brew two full pots of plain water to rinse.

Espresso or pod machine? Some makers name their own descaler, so their manual wins.

How often

Roughly monthly for both (Which? for kettles, Mr. Coffee for coffee makers). Hard water means more often: Mr. Coffee says twice a month.

In your shoes

Citric acid for the kettle first: no smell for the flatmates.

• Hidden tip: boil only what you need. Bournemouth Water advises against reboiling the same water, and Which? says empty the kettle after use.
• Hidden tip: use that jug ring as your timer. When it comes back, descale again.

For everyone else

Any appliance that heats water plays by these rules: acid dissolves scale, scrubbing only scratches.

So, Hannah: it's chalk, not poison. Let me know how the citric acid goes. Have a de-scale-ightful day. Sorry.

Cheat sheet: descaling