Remove the outer peel of the lemons in long strips using a vegetable peeler, and trim away any white pith from the peel with a sharp knife.

Discard the pith and reserve the lemons for some other use, like lemonade.

Place the lemon peels in the bottom of a 2 quart pitcher.  Pour the vodka over the peels.

Let the vodka mixture sit for 5 days at room temperature.

Stir the sugar and water in a large saucepan over medium heat for about 5 minutes or until the sugar is dissolved.

Cool completely, and pour the sugar water into the vodka.

Let stand overnight, covered.

Strain limoncello through a mesh strainer and discard the lemon peel.  Transfer limoncello to bottles and store in the refigerator for 4 hours or until cold, and up to 1 month.