Slice lemons in half, and juice until all juice has been removed from the lemons. Do not discard the lemon rinds, set them to the side.
In a large saucepan combine 4 cups water and sugar. Mix on high until sugar is dissolved then add all the lemon rinds to the pot. Heat for 10 minutes then turn the burner off and let sit for 20 minutes.
Strain the lemon simple syrup into a pitcher then add in the fresh lemon juice and 2 cups of cool water. Chill until cold and serve over ice.