1. Combine vodka and rind in a bowl. Cover and let stand at room temperature for 2 weeks. Strain through a sieve into a bowl; discard solids.
2. Combine 3 cups water and 1 1/2 cups sugar in a large saucepan. Cook over medium heat until the sugar dissolves, stirring occasionally. Remove from heat, and cool to room temperature. Add to vodka mixture.
3. Divide limoncello evenly among 3 sterilized (750-milliliter) bottles, and seal.
Note: Store in the refrigerator up to 1 year.