We descaled six electric kettles every month for a year. Two of them cannot be descaled properly.

Limescale is the actual lifespan determinant for a kettle in a hard-water area, and the feature that decides it — whether you can reach the element — is on no spec sheet.

We bought six electric kettles, used them daily in a hard-water area for twelve months, descaled each one monthly with citric acid, and timed a 1-litre boil at the start and the end.

The finding

Price predicted almost nothing. Element design predicted almost everything.

The £110 kettle was the nicest object in the test and the second-worst performer on the only measure that determines how long it lasts.

Why concealed elements lose

A concealed element sits beneath a flat stainless plate. That is better looking, easier to wipe and protects the element from being knocked.

It also means descaling depends entirely on acid reaching and dissolving every deposit, because you cannot get a brush in there. In practice the acid does most of the job and not all of it, a thin layer survives each cycle, and twelve monthly cycles later there is a film insulating the element that no amount of citric acid will now shift.

An exposed element you can scrub descales completely. That is the whole mechanism, and it is on no packaging anywhere.

The filter nobody checks

Three of the six had spout filters that do not come out.

A removable filter rinses under a tap in five seconds. A fixed one accumulates the scale flakes that descaling loosens, and once it is clogged it stays clogged — which is how you end up with a kettle that pours slowly and shows grit in the cup, and conclude it is worn out.

What this costs in electricity

Scale is an insulator. A kettle losing 19% of its boil speed is drawing power for 19% longer to do the same job.

At a few boils a day that is not a dramatic bill, and it is a reasonable illustration of why this matters beyond longevity: the kettle degrading is also the kettle getting more expensive to run, continuously, in a way nobody attributes to limescale.

What we would buy

An exposed-element kettle with a removable spout filter, in the £25–£45 range, and citric acid rather than vinegar.

If you are in a soft-water area, ignore all of this and buy whatever you like the look of. The distinction that dominated our test barely exists without hard water — which is exactly why no manufacturer mentions it.