Descale your teapot regularly, preferably every 20 to 40 uses, and more often if your water contains a lot of limestone.
To descale your teapot:
• Use commercially available 8° white vinegar:
- Fill the teapot with 1/2 litre of vinegar,
- Let this stand for 1 hour cold.
• Citric acid:
- Heat up 1/2 litre of water,
- Add 25g of citric acid and allow to stand for 15 min.
Empty your teapot and rinse it 5 or 6 times. Repeat if necessary.
Never use other methods of descaling other than the recommended methods.