Mxsmanic wrote:

If you're not thirsty, you're not dehydrated.

Well, you may get thirsty before dehydrating while playing with your joy
stick, but people who work and play in hot climates know that that is
not true. Physiologists know that dehydration can precede thirst. The
military knows it in training troops. Pro sports teams know it. Serious
hikers know it. All plan appropriate water consumption based on planned
fluid losses, not thirst. You also imply in another post in this thread
that the kidneys won't make urine if one is dehydrated:
"If your flight is three hours, typically by the
time the stuff you drink on board starts to find its way to your
kidneys (if it does--it won't if you truly need the hydration)..."

That's not so either, unless you're going into shock. Try not making
bold statements on health issues. You are obviously not qualified.