To a medium saucepan, add 1 cup sugar, 1 cup water, and sliced peaches. Bring to a boil and simmer for 15-20 minutes. Strain the peach syrup through a fine mesh sieve, pressing down on the peaches to get all of the juice. Allow the peach syrup to cool.
To a large pitcher, add lemon juice, peach syrup, and 5 cups of water. Stir well.
Serve over ice and garnish with fresh lemon or peach slices.
Notes
Taste the peach syrup after simmering with sugar. If you prefer a sweeter lemonade, you can add more sugar during this step.
For an alcoholic version of this lemonade, consider adding a splash of vodka or bourbon.