Using a vegetable peeler, remove the peel from the oranges in long strips (reserve the oranges for another use). Using a small sharp knife, trim away the white pith from the orange peels; discard the pith. Put the orange peels in a 2-quart pitcher or large glass bowl. Pour the vodka over the peels and cover with plastic wrap. Steep the orange peels in the vodka for 4 days at room temperature.
In a medium saucepan, combine the water and sugar over medium heat. Bring to a boil, reduce the heat, and simmer for 5 minutes, stirring occasionally, until the sugar has dissolved. Remove the pan from the heat and allow the syrup to cool, about 20 minutes. Pour the syrup over the vodka mixture. Cover and let stand at room temperature overnight. Strain the orangecello through a mesh strainer. Discard the peels. Transfer the orangecello to bottles. Seal the bottles and refrigerate until cold, at least 4 hours and up to 1 month.