1.25 Gallons or Around 5.5 liters (maybe a little less sometimes) of fluids per day. 70-80% of this is water, the rest is milk/drinkable yogurt/green tea (sometimes I drink a lot of this stuff... really healthy) and maybe some natural fruit juices with minimal artificial flavors. Need it as I am consistently active.
The "8 glasses" to stay healthy should be a bare minimum, even for smaller sized people. You can survive on much less, but that does not mean its "enough". You're probably just cutting your lifespan and doing damage to your body.
For those that say they feel "bloated" or "too full of water", I suggest you trickle in fluids throughout the day, rather than trying to down 2 liters within one hour. Make it a habit to carry around some water with you or something. Take a couple sips every 15 minutes. Hope that helps.
Oh and FYI, by the time you are feeling "thirsty", you are already 2 to 3 % dehydrated, and that isnt good. Dont drink because you feel thirsty. Drink on schedule. :p
