The water temperature for black tea should be 90 to 98ºC and for green tea around 80ºC. To draw the best flavour out of the tea the water must contain oxygen. This is reduced if the water is boiled more than once or can also happen if the water is heated in a microwave. You should never boil water in a Microwave. 100ºC is the temperature at which kettles are designed to heat tea. In the case of using the microwave, there is no way of showing the temperature of the water. The mechanism for boiling water through the microwave differs completely from the kettle. Consequently, the results and how the tea would taste differs. The kettle gives the water the uniform temperature needed. That's why the kettle is highly recommended for usage for boiling water for tea. In contrast, the microwave will give you hot water but the water's temperature is not consistent throughout the cup. In all ways, the kettle is better than the microwave.