It cleans out the adrenal system
That isn't true... If you drink a lot of "light" or water based fluids it can be. The more of those you drink, the more it will dilute the effects of "darker" or salt/carbohydrate rich liquids (soda, alcohol, etc) which more easily leave concentrations of their sugars and salts in passing urine. To the last person, if you drink coke constantly each day you won't have light colored urine unless there is something else in your body naturally causing that effect.
Because you drink a lot if you drink a lot of any fluids you're urine will be light in color