Electric kettle fan here, too. When I want just one cup, I pour the cold water from the cup I will be using into the pot, and only heat that one cup. I do the same to use my French press for coffee in the morning. That way I am only heating th water I need.

we have hard water, so about every ten days I put a little vinegar and acupuncture of water in the pot, heat it and let it stand for a while.