Various type of tea from Georgia
In the West, water for black tea is usually added near the boiling point of water, at around 99 °C (210 °F). Many of the active substances in black tea do not develop at temperatures lower than 90 °C (194 °F). Lower temperatures are used for some more delicate teas. The temperature will have as large an effect on the final flavour as the type of tea used. The most common fault when making black tea is to use water at too low a temperature. Since boiling point drops with increasing altitude, it is difficult to brew black tea properly in mountainous areas. It is also recommended by the British that the teapot be warmed before preparing tea, easily done by adding a small amount of boiling water to the pot, swirling briefly, then discarding it.
Western black teas are usually brewed for about four minutes and are usually not allowed to steep for less than 30 seconds or more than about five minutes (a process known as brewing or mashing in Britain). In many regions of the world, however, boiling water is used and the tea is often stewed. For example in India, black tea is often boiled for fifteen minutes or longer as a strong brew is preferred for making Masala chai. When the tea has brewed long enough to suit the tastes of the drinker, it should be strained while serving. Popular varieties of black tea include Assam, Nepal, Darjeeling, Nilgiri, Turkish and Ceylon teas.