At sea level, water boils at 212°F. On top of a mountain? It boils at a lower temp. Science!
At 10,000 feet, it boils around 194°F. That’s still hot enough to kill typhoid. But it takes longer. Boil for 3 minutes up there.
So if you’re hiking Everest, don’t rush your tea. Typhoid doesn’t care about your summit photo.