If you microwave the water for your tea in front of someone raised in the UK, expect to get some dirty looks. The prejudice against this convenient preparation method may feel like outdated snobbery, but it has basis in science. According to Slate, tea really does taste better when it's made with a kettle instead of a microwave.
The temperature of the liquid is essential to a properly brewed cuppa. Water should reach a roiling boil before it's poured over the bagged or loose tea leaves. This is easy to do with tea kettles—both the stovetop and electric varieties. The water at the bottom of the vessel warms up when the burner or electric heating element is turned on. As the heat rises, water throughout the rest of the kettle comes to an even temperature of 212° F, or the boiling point for water.
Microwaves don't heat from the bottom up. Instead, they produce electromagnetic waves that bounce randomly around the box. This why your reheated leftovers can be partially frozen in some places and mouth-scorchingly hot in others.
Microwave energy is hard to control, which is bad news for tea-drinkers who use it as their primary heating method. Water that's still lukewarm in spots after coming out of the microwave is less effective at extracting flavor compounds from tea leaves. Over-heated liquid can be equally disastrous. When water exceeds 212° F by a few degrees, it can destroy the compounds that give tea its desired flavor.
This isn't a problem with tea kettles. A conventional kettle's metallic body prevents it from getting too hot, while electric kettles are designed to turn off automatically once the water reaches its boiling point.
Microwaves are the perfect tool for many kitchen tasks, but brewing tea isn't one of them. If you enjoy a daily cup of tea, it may be time to invest in a kettle for your boiling needs. After bringing the water for your tea to the ideal temperature, there are other steps you can take to improve the quality of your brew. This is how long you should be steeping your tea, according to science.