Bring 6 cups of water to a boil.
Add tea bags to the water, remove from heat, and steep for 5 to 7 minutes.
Remove tea bags.
Add sugar to hot tea mixture and stir to dissolve.
Pour the hot tea mixture into a pitcher and add 2 cups of cold water and lemon juice.
Bring the remaining 2 cups of water to a low boil.
Add frozen berries, minus the berries for garnish.
Simmer berries for 5 minutes.
Pour the berry juice through a screen sieve into the tea mixture.
Chill in the refrigerator until cool.
Serve over ice with reserved berries for garnish.