Hard water is water that contains calcium or magnesium mineral ions often in the form of carbonate. These ions do not pose any health threat, but they can engage in reactions that leave insoluble mineral deposits. Hard water mineral deposits, or scaling, is the precipitation of minerals which form lime scale. How to Descale? Fill the kettle with 1 cup of vinegar or lemon juice and 2 cups of water. Boiling the liquids and leave it for 2 hours, then use cloth to clean and wipe. Rinse the kettle with clean water, and dry with a soft, clean cloth. Repeat as needed. Note: Its normal if your kettle exposes spot or rust on the stainless steel bottom after the first use, if the water quality in your area is so hard. Here are some steps to descale the kettle: 1. Unplug the kettle and pour out all water. Make sure the kettle is cool. 2. Squeeze half a lemon into the kettle, or add 1⁄2 US cup / 118 mL of distilled vinegar into the kettle. 3. If the kettle has thick scale buildup, scrub the kettle’s inner walls with a non-scratch scrub sponge. 4. Add 2 US cups / 473 mL of water. Boil the mixture. 5. Pour out the mixture, then wipe off any remaining scale with a non-abrasive cloth, sponge, or cleaning brush. 6. Repeat as needed.