In a small saucepan over medium heat, combine water, sugar, and lemon zest. Bring to a boil, then reduce heat and simmer for about 2 minutes. Remove from heat and allow it to cool.
Stir in 2 cups of freshly squeezed lemon juice
Transfer to a 9 x 13 metal baking plan. Place in freezer for about 3 hours. Stir with fork every half hour for the first hour.