Heat 2 cups of water with sugar, until sugar dissolves. Continue to heat for 5 minutes or so until it starts to thicken up, then add the rest of the water, zest and juice. 

Let cool to room temperature. 

Put the blueberries and blackberries in a blender and puree.

Stir berries into the lemonade, cover and refrigerate for 2 to 3 hours. If you don't like"chunky" lemonade strain the lemonade before serving.