For stronger lemon flavor, add some juiced lemon halves (wash lemons before squeezing) to the lemonade.
In a large saucepan, heat sugar and 1 cup water over medium-high heat, stirring, until sugar dissolves; remove from heat.
Stir in lemon juice and 6 cups water. Strain, if desired, into a large container; refrigerate until cool, 30 to 40 minutes. Serve over ice.