Hi Hacksaw,

Altitude will also play a factor, the boiling point temperature of water gets lower the higher the altitude.

http://en.wikipedia.org/wiki/Clausius-Clapeyron_equation

This is crucial, as prolonged boiling of water, or water that is boiled twice, drives off the dissolved oxygen in the water, making the tea taste flat . There can sometimes be a fine point between a decent cup of tea and bacterial infection at high altitudes. Thats why a pressure cooker is a good idea at altitude.

People who live at high altitudes, like Tibetans, drink their tea while it is bubbling with boiling. Many Tibetans who moved to India suffered serious burns when they drank their boiling tea at sea-level.