Published March 1, 2010. From Cook's Illustrated.
You could boil water, let it cool, and check with an instant-read thermometer for the perfect cup of tea—or let technology do it for you.
Tea connoisseurs know that lower water temperatures (from 165 to 195 degrees, rather than 212 degrees, or boiling) mean a better brew; similarly, water between 195 and 205 degrees will produce a fuller-bodied, less bitter coffee. While you could boil water, let it cool, and check with an instant-read thermometer, a new breed of electric kettles designed to bring water quickly to a range of different temperatures (and, in some cases, to hold it there) promise to save time and effort, with precise results.
We found five models; all but one boasted automatic shutoff, a separate base for cordless pouring, and a visible water level, features we like in an electric kettle. Four of the five brought water to a boil in less than five minutes, about the same as our favorite standard electric kettle. Our winner wowed us with its ability to hold water at the desired temperature for up to 10 hours, but we balked at its price and its ungainly size. For tea or coffee connoisseurs who don’t mind spending $100, our second place finisher is fast, accurate, and holds water at temperature for up to 40 minutes.