How to Make It
Place 1 cup water and 3 cups blackberries in a blender; process until smooth. Press blackberry puree through a sieve into a large pitcher; discard seeds. Add remaining 5 cups water, sugar, and juice to pitcher; stir until sugar dissolves. Place 1 lime slice and a few blackberries, if desired, into each of 8 glasses; pour about 1 cup limeade over each serving.