questions! : carrying water

[David planning Le Chemin de St Jacques/El Camino de Santiago]

> In dry air, respiratory loss of water results in a relative
increase in blood sugar and blood electrolytes, which can only be compensated
by plain water or diluted drinks which have electrolytes and sugar....

And the other side of the coin is a condition called hyponatremia caused
by drinking too much plain water and not enough salt... the trailheads at
the Grand Canyon now warn about this, advising hikers to eat as well as drink.
It can become a serious medical situation... here's one of the many web
sites on the subject (find more with google)

http://www.rice.edu/~jenky/sports/salt.html