01 - Combine sugar and 1 cup of water in a small saucepan. Stir over medium heat until sugar dissolves completely. Remove from heat and allow to cool.
02 - In a large pitcher, combine freshly squeezed lemon juice, cooled simple syrup, and remaining 3 cups cold water. Stir thoroughly.
03 - Taste the mixture and adjust sweetness or tartness by adding more sugar or water as preferred.
04 - Refrigerate for at least 30 minutes or serve immediately over ice.
05 - Optionally, add lemon slices and fresh mint leaves before serving.