If you notice a stain on the bottom of your kettle's interior that resembles rust, don't worry! It is likely not rust, but actually a harmless buildup of minerals called limescale (comprised of mainly calcium carbonate). Limescale is a direct result of heating up water and thus inevitable with all kettles. Depending on the mineral concentration in your water, it is bound to show up sooner or later.
To get rid of limescale, mix a 1-to-1 solution of water and white vinegar (250 mL of each) and pour it in your kettle. Let it sit overnight and in the morning, heat your kettle to a boil for 5 minutes (turn the hold switch off if it's on) and let sit for at least a half hour.
Afterwards, rinse out the kettle with fresh water to get rid of residual vinegar. If you notice lingering traces of vinegar, fill your kettle up and add a tablespoon of baking soda before heating it up again. Baking soda does a good job of neutralizing the scent of vinegar and will help remove stubborn limescale stains.
If limescale stains remain after this process, citric acid is slightly more powerful than vinegar and it should knock out residual limescale. If this does not resolve the issue, please reach out to us and we'll take care of you!
Caution: Scrubbing the bottom of your kettle with steel wool or an abrasive brush will ultimately make limescale worse and may also result in the development of rust. Please use a sponge or soft brush to clean the inside of your kettle.