 More than half of all dishwashers in the city are undocumented workers, as are a third of all sewing machine operators, painters, cooks, construction laborers, and food preparation workers.Undocumented workers also make up close to 30 percent of the city's automotive service technicians and mechanics, waiters, maids and housekeeping cleaners, and carpenters.The five occupations with the most undocumented workers in New York City are cooks (21,000), janitors and building cleaners (19,000), construction laborers (17,000), maids and housekeeping cleaners (16,000), and waiters (15,000).