If you leave water in your stainless steel, copper, ceramic, or enamel tea pot you can damage it with the stagnant water. Just the word stagnant should make you want to empty the pot. The minerals and water buildup lime scale that will corrode the metal pot lining. Also, if you re-boil that water the oxygen and other natural gases will give your tea a dull taste. UGH! Descale your kettle once in a while by heating up a mixture of half water and half white vinegar. Soak overnight. In the morning pour it out, rinse, and heat up fresh water. Most importantly, dump the water in the kettle after each use. If you cool it, you can use it to water your plants!