5 cups of green tea a day is not nearly the same as a pot of coffee. There is MUCH less caffeine in green tea. Green tea (and even better is herbal tea) is basically the same as water.
Many people will not like to admit this... but drinking a soda counts toward some of your hydration counts for the day. Is it better than water? NO
But no matter if you drink green tea or water... it's basically the same. I won't say that about many things... although as I said earlier... herbal teas are even better because they contain zero caffeine.
It is possible to drink too much water. Actually a lot of marathon runners/endurance athletes are being taught not to drink so much. It lowers their sodium levels and causes problems. Amateurs typically don't drink enough, but there are those that have been taught to drink whenever possible during an event... and now scientists are asking them to reduce the water intake.
depends on the size of the cup. 5 cappucino style mugs of green tea is like 50oz of tea...which would likely have the same amount of caffine as 36oz of coffee.
Green tea contains less caffeine than coffee: there are approximately thirty to sixty mg. of caffeine in six - eight ounces of tea, compared to over one-hundred mg. in eight ounces of coffee. BIG DIFFERENCE
How much I drink depends on my menu/fitness routine and mood. Most days I aim for 60-80 ounces of water.