How often should you descale a kettle? Electric kettles, water boilers and citric acid

How often: every 1–3 months, monthly with hard water

Descale a kettle or water boiler about every 1–3 months. Manufacturers and testers land in roughly the same place:

Appliance	Who says	How often
Water boiler	Zojirushi	Every 1–3 months, more often with mineral-rich water
Water boiler	Tiger	Every 2–3 months
Electric kettle	Russell Hobbs (instructions for model 21274)	At least monthly
Electric kettle	Which?	Every month or so

The range is wide because limescale builds up at very different speeds depending on what’s in your water. Lean toward monthly if:

• Your water is hard. The Drinking Water Inspectorate explains that hardness comes from dissolved calcium and magnesium and varies with local geology. Which? notes that in hard water areas limescale builds up in appliances quite quickly. Your water company can tell you how hard your supply is.
• You boil a lot. Scale is left behind every time water is heated, so a kettle that runs all day collects it faster than one used once in the morning.
• You have a glass kettle. Which? says glass kettles in hard water areas may need descaling more often.

If you’re not sure where you fall, start at monthly. If the kettle is barely scaled each time, stretch it to every two months.

Russell Hobbs also points out a practical reason not to let it slide: products returned under guarantee with faults caused by scale are subject to a repair charge.

What limescale is, and why it matters

Limescale is minerals from your water, not dirt. Which? describes it as a chalky deposit made mostly of calcium carbonate, and says it’s harmless to consume. Tiger explains that the red dots, milky white or rainbow patches and white flakes that appear in water boilers come from minerals such as calcium, magnesium and iron, not from corrosion or the coating peeling off.

It’s still worth removing:

• Slower, less efficient heating. The Drinking Water Inspectorate says scaling of heating elements shortens their life and makes appliances less efficient; Which? adds that it takes longer, and more energy, to boil.
• Taste. Which? notes flakes in your tea and, in bad cases, a slightly bitter aftertaste.

Filtered water can help. Which? suggests using filtered water in your kettle to reduce build-up, and the Drinking Water Inspectorate says some jug filters may minimize scale in kettles. If you use one, keep up with changing the filter cartridge.

How to descale a water boiler with citric acid

Use the citric acid cleaning cycle in your manual. Zojirushi’s steps for its water boilers:

1. Dissolve one packet of citric acid cleaner in a cup of warm water.
2. Pour it into the inner container and fill with water to the maximum line.
3. Close the lid, plug in, and press and hold the Reboil button for more than 3 seconds to start the descaling mode (button names vary by model).
4. When it finishes, unplug, remove the lid and pour the water out from the marked spot.
5. Rinse out the citric acid: fill with fresh water, boil, dispense about a cup through the spout, let it cool and pour the rest away.

Zojirushi says bottled lemon juice from concentrate can stand in for the cleaner, but not freshly squeezed juice, which can get caught in the pump.

Tiger’s method for its citric acid powder is similar: one bag (about 30 g) in the inner container, fill to the maximum level and stir, boil, keep warm for about three hours, then empty it. Rub off any remaining stain with a sponge and rinse thoroughly. If your boiler has a dedicated citric acid cycle, Tiger says to follow the boiler’s manual instead.

How to descale an electric kettle

Citric acid, vinegar or a descaler all work. Check your manual for which one it allows. Which? describes all three:

• Citric acid: boil a half-full kettle, switch it off and unplug it, then add one to two tablespoons of citric acid. Leave it for 15–20 minutes, pour it out and rinse a couple of times.
• White vinegar: fill the kettle about three-quarters full with equal parts white vinegar and water, bring it to the boil and leave it until it’s completely cool. Rinse, then boil and empty fresh water two or three times to get rid of the vinegar taste.
• Descaling powder: follow the brand’s instructions; it’s usually a sachet in a recently boiled kettle for about 10 minutes. Rinse well, or boil and empty once more, before making a drink.

Russell Hobbs’ instructions say to use a proprietary descaler and follow the directions that come with it. Which? says a long-handled scrubbing brush can help with stubborn patches; if your manual warns against scrubbing the inside, follow the manual.

Common mistakes

• Waiting until you see flakes. Heavy scale may take a second round or some scrubbing; Which? notes stubborn patches can need a brush, and Tiger says to rub off any stain that remains with a sponge.
• Skipping the rinse. Boil and pour away fresh water after descaling, and on a water boiler dispense some through the spout, so the next cup doesn’t taste of citric acid or vinegar.
• Using freshly squeezed lemon in a water boiler. Zojirushi says it can get caught in the pump and damage the boiler; use citric acid or bottled lemon juice from concentrate.
• Leaving water sitting in the kettle. Which? suggests emptying it after use to slow build-up.
• Ignoring the manual. Cleaning cycles, amounts and allowed products differ by model, and scale damage may not be covered under guarantee.

How to remember

Descaling every month or two has no natural trigger. It usually waits until someone sees white flakes in their tea, and by then nobody remembers which weekend it was last done. When everyone in the house uses the kettle, everyone also assumes someone else took care of it.

Tracking “descale kettle” as a recurring item makes the next one obvious, and whoever does it can mark it done. Other monthly jobs fit the same weekend: cleaning the washing machine and cleaning out the fridge. If you use a filter jug, track the filter cartridge alongside it.