A chalky layer inside a kettle is usually calcium carbonate left behind as water is heated. It is common in hard-water areas and is normally a maintenance issue rather than a sign that the kettle is unsafe.
Start with a safe descale
Switch off and unplug the kettle, follow its care instructions, and use a manufacturer-approved descaler or a suitable diluted citric-acid solution. Rinse thoroughly and boil a full kettle of clean water once or twice before use. Never immerse an electric base or mix cleaning chemicals.
Why does it keep returning?
Descaling removes existing deposits but does not change the minerals in the incoming supply. Faster buildup can indicate harder water, a frequently used kettle or water that is repeatedly boiled.
When should you investigate further?
If scale is appearing across taps, shower screens and heating appliances, check your supplier’s hardness information before buying equipment. A kettle filter may improve convenience, while whole-home treatment requires a different assessment.
Read what hard water means or use the water-treatment tools before comparing options.