How to Make It
In a saucepan, combine 4 cups of the water with the sugar, star anise, ginger and mint. Bring to a boil. Remove from the heat and let stand for 30 minutes. Strain the syrup and refrigerate.
In a very large pitcher or bowl, stir together the grapefruit, orange and lime juices. Stir in the syrup and the remaining 4 cups of water. Serve over ice.
To make 1 cup of juice, you'll need 5 to 6 limes, 2 to 3 medium oranges or 1 medium grapefruit. For this recipe, you'll need about 25 limes, 12 oranges and 8 grapefruits; or you can buy store-bought, fresh-squeezed orange and grapefruit juices so you'll only have to squeeze the limes.