Plumbers plan, install, maintain, inspect and repair plumbing systems, fixtures, equipment and controls in residential and commercial buildings. Some plumbers install piping systems in new home construction, commercial, industrial and public buildings. Others are experts in the retrofitting, repair and maintenance of existing systems. In smaller communities, plumbers generally do a wider variety of plumbing and related tasks, including installing private sewage disposal systems and potable (drinking) water distribution systems. Plumbers must be able to read blueprints and project specifications to determine the layout for the plumbing and other materials. They may work with pipes made from iron, steel, lead, copper, plastic, glass and cement and need to know the particular characteristics of the substances being carried in the pipes.

Construction companies, heating and plumbing contractors, and maintenance departments of plants, factories, governments and schools are all major employers of plumbers.