First, in a medium saucepan over high heat, combine the 32-ounces of water and sugar. Stir the mixture until all the sugar has melted, remove it from the heat and set it aside.
Next, in a large tea pitcher, add the 2-cups of ice.
After that, add the seltzer water, tequila, lemon juice, and most of the simple syrup and stir everything to mix it together.
Last, add freshly sliced lemons to the drink and serve it in 6-8 ounce glass, half-filled with ice.
The calories listed are an approximation based on the ingredients and a serving size of about 8-ounces. Actual calories will vary. The drink can be made in advance and be stored in your fridge for up 24-hours.