For a colloquial American use, see White House Plumbers; in London, see Worshipful Company of Plumbers

A plumber is a tradesman who specialises in installing and maintaining systems used for plumbing, heating, drainage, potable (drinking) water or industrial process plant piping. (In most jurisdictions the piping for heating systems are installed by steam-fitters, pipefitters or gas-fitters.)

The most famous plumbers are most likely the fictional Mario and Luigi from the popular Nintendo game series Super Mario Bros.

"If I would be a young man again and had to decide how to make my living, I would not try to become a scientist or scholar or teacher. I would rather choose to be a plumber or a peddler in the hope to find that modest degree of independence still available under present circumstances." -- Albert Einstein, The Reporter , 18 November, 1954

Shortly after making this remark, the Plumbers and Steamfitters Union, A.F.L. in Washington, D.C. voted to grant Einstein an honorary membership. Einstein was reportedly well pleased with this honor.