Grape and Blueberry Iced Tea

Combine all the ingredients except the teabags in a large pot. Stir until the sugar has dissolved. Bring to a simmer and allow to simmer for 10 minutes while gently pressing the berries and grapes against the side of the pot to break them up. Strain through a sieve, discarding the fruit pulp and skins. Add the teabags to the hot liquid and allow to steep for 10 minutes. Chill, and then dilute with water according to taste. Serve in a tall jug with lots of ice.