Preheat oven to 350 degrees
Combine diced peaches and sugar in a bowl for 20 minutes.
Add water and stir.
Pour peach mixture into 9 x 13-inch baking dish.
Sprinkle dry cake mix evenly over the peaches.
Arrange butter slices evenly over cake mix.
Bake for 30-40 minutes until the top is golden brown.
Remove and cool.
Cut into squares and serve with whipped cream and a peach slice, or a scoop of vanilla ice cream.
