Add the blueberries and half of the water to a blender or food processor. Blend until smooth.
Pour the blueberry mixture into a large pitcher.
Add the lemon juice, sugar, and remaining water. Stir until the sugar is completely dissolved.
Serve immediately over ice, if desired.
Notes
If you do not have fresh blueberries, use frozen ones that have been thawed in the fridge. You do not want them to be frozen when you blend them.This lemonade will be good in the fridge for about 6 days. You can also pour this lemonade into a popsicle mold for a yummy frozen treat.