Staying hydrated is crucial any day of the year, but it is especially important when traveling. This is because when you are flying, your body dehydrates faster. You feel thirstier, and your skin dries out. It's imperative to remember to get your eight cups of water intake and probably, even more than usual, to be on the safe side. If you don't, you can feel very sick while up in the air.
So it might be a good idea also to book an aisle seat so you can drink all the water you want and have no problem making your way to the bathroom.