2 to 3 cups premium ginger ale (such as Fever Tree), to taste
Bring the water to a boil in a large saucepan. Add the tea bags and sugar, stirring to dissolve the sugar, and let steep for 10 minutes. Discard the tea bags, pour the tea into a large bowl, and let cool.
Stir in the bourbon, and lemonade and orange juice concentrates. Pour into a large freezer bag, squeeze out the air, and close tightly.
Freeze until the slush is firm all the way through, preferably overnight. (The frozen slush base keeps in the freezer for up to one month.)
To serve, scoop slush into a glass. Slowly pour in ginger ale without stirring, and serve straightaway.