In a small saucepan, combine 2 cups water and 1 cup granulated sugar.
Heat over medium, stirring occasionally, until the sugar is fully dissolved and the mixture reaches a gentle simmer; remove from heat.
Pour the syrup into a heatproof jar or container and let it cool to room temperature.
When the syrup is room temperature, add ½ cup fresh lime juice and ½ cup fresh lemon juice, then stir to combine.
Transfer to a sealed container and refrigerate; it will keep 2–3 weeks in the fridge or up to 3 months in the freezer.
Shake or stir before using.
Notes
Tips
It should be bottled in a well-sealed airtight container and stored in the refrigerator for up to three weeks.
In a freezer safe container, you can freeze it for up to three months.