If you drink a gallon of water you won’t remain in your seat for 3 hours. You’ll be up walking to the loo.
>> If you drink a gallon of water you won’t remain in your seat for 3 hours. You’ll be up walking to the loo <<
Not necessarily. The exceedingly dry air in the cabin means you’ll lose a lot more moisture via your skin than you lose in ordinary ground-level conditions.
And by the way, I didn’t mean to suggest that you drink that gallon all at once. Just space it out over your 17-hour flight — and you’ll be fit as a fiddle when you land.