RomeoMike writes:

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.

I was born and raised in a desert. You get thirsty when you get
dehydrated; it is an extremely reliable indicator of dehydration.

Physiologists know that dehydration can precede thirst.

Only under very unusual circumstances of rapid water loss, which are
not likely to ever occur while flying a general aviation aircraft.
Essentially, you have to be vomiting, urinating, experiencing
diarrhea, or perspiring profusely to dehydrate that rapidly. None of
these is very probable in an aviation context.

The military knows it in training troops. Pro sports teams know it. Serious
hikers know it.

None of them are pilot GA aircraft, however, and there is no
comparison. You're no more likely to dehydrate significantly in an
aircraft than in a car.

All plan appropriate water consumption based on planned
fluid losses, not thirst.

Only when TBW losses are expected to be extremely rapid. That does
not apply to general aviation.

You also imply in another post in this thread
that the kidneys won't make urine if one is dehydrated:

They will concentrate as much as they can. If dehydration is extreme,
however, they will go into acute renal failure. Again, however, this
is never likely to occur in an aviation context.

If it burns when you urinate, that's one sign that you are seriously
dehydrated. A simple test is to make sure your bladder fills every
3-5 hours, and check to make sure that your urine is not brightly
colored. If it is lightly colored and you urinate at least with this
frequency, it's unlikely that you are significantly dehydrated.

That's not so either, unless you're going into shock.

It's normal physiology.

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