Step 1

Begin by making a simple syrup, combining the sugar and 1 cup of the water in a small saucepan.  Bring to a gentle simmer over low heat, just until the sugar is completely dissolved.  Remove from the heat to cool.

Step 2

Cut each lemon in half and squeeze over a measuring cup, until you have 1 cup of lemon juice.

Step 3

Add the simple syrup and lemon juice to a large pitcher, followed by the remaining 4 cups of water.  Stir and adjust to taste, adding a few tablespoons of sugar or the juice of half a lemon if it is either too sweet or too tart.

Step 4

Add in the 2 cups of blueberries and the basil leaves and stir.  Use the back of a long wooden spoon to squeeze the blueberries against the side of the pitcher, breaking up some of the whole blueberries.

Step 5

Immediately before serving, add the liter of seltzer to the pitcher.

Step 6

Serve in a highball glass filled with ice and the liquor of your choosing.