If you have a tea kettle with mineral buildup, there are a few ways to remove it. Boiling water and vinegar is one method. Fill the kettle with equal parts water and vinegar, then bring it to a boil. Let it sit for 30 minutes, then empty and rinse the kettle. You can also use citric acid or CLR (calcium lime rust) remover. Follow the instructions on the package for how much to use and how long to let it soak. Once the mineral buildup is gone, be sure to rinse the kettle well before using it again.