Step 1Make a simple syrup by combining the sugar and water in a small saucepan and bringing it to a boil over medium heat. Reduce the heat and simmer until the sugar is dissolved and the syrup is clear, about 1 to 2 minutes. Remove from the heat and cool to room temperature.
Step 2While the syrup cools, squeeze the lemons and limes, straining the pulp and seeds. Add the juices to the cooled syrup. Refrigerate to store.