Originally Posted by Dollarmansteve

8-9 glasses of water = 2 Litres (1/2 gallon). It doesn't really matter what form that water is in. Coke counts, coffe counts, tea counts, juice counts, etc, etc.

Obviously, pure water is the best choice. The caffeine is the diuretic in tea / coffee /coke - it does NOT affect your ability to absorb liquids, that is - it will NOT dehydrate you (this is a myth). What it does do is sap your body of electrolytes (potassium, sodium) which changes the balance of intracellular vs intercellular water. So it creates thirst - but not dehydration (thirst is caused by an imbalance of electrolytes and/or blood sugar levels).

Simply adding the excess liquid from a caffeinated beverage will cause urination (chug 1 litre of water and see how much you pee.....), the diuretic will just change the chemical balance of the urine.