Boil 3 cups water, 3 cups grape juice and the green coffee bean powder (if using) in a pot over medium heat. Remove from heat and add the teabags. Let steep 30 minutes.
Bring to a boil 1 cup water and 1 cup of sugar in a medium pot over medium-high heat, stirring to dissolve the sugar. Remove from the heat and add the ginger. Let steep for 30 minutes. Pour through a fine sieve and discard the chunks of ginger.
Remove tea bags from the steeped tea and pour into a 2 quart or larger pitcher.
Add the ginger simple syrup and the two cups of very cold water and mix.
Add mixed berries. Place pitcher in the refrigerator for a minimum 1 hour to allow the flavors to blend and the tea to get chilled.
Add a few frozen blueberries and/or raspberries to individual glasses for an extra berry touch.