Right. Back in the olden days, when I was a girl, this was actually covered in school. While water is "boiling" at a lower temp and some foods will cook more slowly, some will never be "done." For example, the starch in potatoes usually won't break down unless one cooks them in a pressure cooker at elevation.

People who count on boiling water to kill Giardia, etc., will need the water to boil longer to kill the spores. It might be more weight- and cost-effective to filter water in this case. Mountains on the east coast probably are not high enough for altitude to have this impact.

CM