Such a fun thing to make with kids (and sell in your front yard to raise money for worthy charities). If you make it yourself, sugar is not corn syrup and you can control the balance of sweet and sour.
2 cups water
2 cups sugar
8 – 12 limes, juiced
ice and additional water
Make a simple syrup: combine water and sugar in a saucepan. Bring to a boil and then stir until the sugar dissolves. Remove from heat and allow to cool completely. If you have any leftover, it stores well in the fridge in a closed glass container for several months.
Pour lime juice into a pitcher. Gradually add cooled simple syrup until sweet and sour ratio works for you, then add water to de-intensify, and ice to chill. Refrigerate until you serve and serve over more ice. (I used 8 limes, 1.5 cups simple syrup and 1 cup additional water)
Enjoy, sell at an exorbitant price or give away to neighbors.