The word "plumber" dates from the Roman Empire

The word "plumber" dates back to the Roman Empire. In Roman times lead was known as plumbum in Latin which is why the periodic table of the elements uses the symbol of 'Pb' for lead. Roman roofs used lead in drain pipes and some were also covered with lead, lead was also used for piping and for  baths production.

In past times people who worked with lead was called a plumber as can be seen from an extract of workmen fixing a roof in Westminster Palace and were referred to as plumbers Plumber, working about the roof of the pantry of the little hall, covering it with lead, and fixing various defects in the roof of the little hall". A person with knowledge in working with lead was first known as a Plumbarius this was later shortened to plumbers.