Place the basil and one cup of blueberries into a large pitcher. Gently muddle and set aside.
Combine the lemon juice, one cup of water, honey, and the remaining blueberries in a saucepan over medium-high heat. Bring to a low boil, stirring to dissolve the honey. Once the blueberries have released their juice and color, pour the mix through a fine mesh strainer into the prepared pitcher.
Pour the remaining water into the pitcher along with a handful of ice. Stir to combine. Serve cold, garnished with lemon slices if desired.