In a small saucepan over medium heat, combine 0.5 cups of the filtered water with the granulated sugar.

Stir the mixture continuously until the sugar crystals have completely dissolved to create a simple syrup.

Remove the syrup from heat and allow it to cool to room temperature (approximately 21°C).

In a mixing pitcher, combine the cooled simple syrup, the remaining 2 cups of water, and the lemon juice.

Whisk the mixture thoroughly to ensure a homogenous solution, then stir in the lemon zest.

Pour the liquid into popsicle molds, leaving 0.25 inches of headspace at the top to allow for expansion during the phase change.

Insert popsicle sticks according to the mold manufacturer's specifications.

Place the molds in a freezer set to -18°C or lower for a minimum of 4 hours or until the cores are fully solidified.