Combine 4 cups water and the ½-1 cup white granulated sugar* in a medium saucepan over medium heat. Heat until the sugar is dissolved, then cool to room temperature.
In a large pitcher, combine the cooled sugar water, 1 cup freshly squeezed lemon juice, and 1 cup unsweetened pomegranate-cranberry juice. Stir to combine.
Just before serving, stir in the 1 ½ cups sparkling lemon-flavored water. Fill glasses with ice and pour the sparkling pomegranate lemonade into glasses.
Add a small handful of pomegranate arils, and garnish glasses with lemon slices and fresh mint as desired.
Notes
*You'll want to reduce this if you get a sweetened pomegranate juice.