Combine 1 cup of water, sugar, blackberries, and blueberries in a saucepan and place over medium-high heat. Stir until the sugar has dissolved and then bring to a boil. Reduce the heat and simmer for 15 minutes. Remove from the heat and strain through a fine mesh strainer into a pitcher.

Heat 4 cups of water in a large pot over medium-high. Heat until it comes to a boil. Add the earl grey tea bags and vanilla bean. Turn off the heat. Let steep for 6-8 minutes. Remove the tea bags, transfer to a pitcher, and stir together. If you would like your tea to be slightly less sweet, add additional hot water.

Allow the combination to cool completely and then store in the refrigerator overnight before serving.

To serve, prepare a glass with ice and a few fresh berries. Pour 12 ounces of the berry tea and 7 ounces of club soda and stir slightly.