Plumbers install, maintain, and repair the water and drainage systems in homes and commercial buildings, and may also set up bathroom and kitchen fixtures and water-based appliances. Plumbers usually attend a vocational or technical training program leading to a certificate or associate's degree in plumbing technology. Licensing requirements for plumbers vary by state, but most plumbers must undergo an apprenticeship, during which time they work under the supervision of experienced technicians. The median hourly pay for plumbing contractors in 2006 was $20.44. Jobs in this field are expected to grow by 11 percent by the year 2016.