Add water to a large pot and bring to a boil. Add the sugar and stir until the sugar dissolves. Turn the heat off.

Add the frozen juice concentrates and stir until all the juice is melted.

Pour the juice mixture into a large freezer-safe container (a beef bucket is recommended).

Add the Iceberg vodka and pineapple puree. Stir to combine.

Place in the freezer and freeze at least overnight.

Once a day for 2-3 days, check the slush and mash it with a potato masher.

To serve, place a scoop in a coupe or rock glass and top with club soda.