C'mon people, this is serious stuff!
Millions live and much tea is grown at the altitudes you are talking about. Tea is blended for the region where it is marketed, including the water composition. I don't know about the altitude, but I bet if you bought your Typhoo in Colorado it would be different from the stuff in Colchester.
Good topic for a Web search, this; I found this after a Google search on "tea and "high Altitude"" - doesn't actually mention tea at altitude but you can always try some more.
http://homecooking.about.com/food/ho...tude/index.htm
You could brew on the deck and microwave it in the air, I suppose!
[This message has been edited by fobotcso (edited 04 November 2000).]