In a saucepan, combine diced peaches, lemon zest, sugar, and 2 cups of water. Bring to a boil over medium heat, stirring to dissolve the sugar. Once boiling, reduce heat and let it simmer for about 5 minutes until peaches are soft.

Remove from heat and allow the mixture to cool slightly.

Using a blender or immersion blender, puree the peach mixture until smooth. If desired, strain the puree through a fine-mesh sieve to remove pulp for a smoother lemonade.

In a large pitcher, combine the peach puree, fresh lemon juice, and the remaining 4 cups of cold water or sparkling water. Stir well to mix.

Refrigerate until chilled. Serve over ice and enjoy!