I drink huge amounts and have since I was a teenager.  I've never given a thought to "hydration" (except for some running-specific cases), I just like it.  If it's not available, I'm okay.  I think it's kind of silly to carry water bottles everywhere like a lot of people do.  I see Americans traveling overseas carrying bottles around at all times because they need to "hydrate".  It's overkill.  The locals somehow survive without carrying bottles at all times.

I took a group to the zoo in Belize and was waiting outside of it.  A bus of Americans pulled up and every single person who got out was carrying a water bottle.  For a one-hour stroll around a well-shaded zoo.  Dehydration is bad, but you don't need to be tethered to the water bottle.  And they could have just drank enough before they got off the bus.

Then again, I've seen some close calls the other way.  When I take students on a three-hour hike through the jungle (partially in the sun) in the middle of the day in Belize, I tell them to take at least twice as much water as they think they'll need.  Still some will just have their cute little water bottles and we've had to send guys up the trees to get coconuts to rescue kids who looked to be in trouble.

I hate carrying water when running and through trial and error I found out that I needed to drink 64 oz before a 1.5 hour morning run in Belize.

So, in summary, hydration is not important.  Except when it is.  Hope that's clear.