A plumber was a worker who fixed plumbing.
In 1985, the plumber Pietro Rossi was transported across dimensions when he entered a house on the outskirts of Rome and tried to fix a blockage in the pipes. (COMIC: Dungeon of the Lost)
Winston Blunt was a plumber in 1989. (COMIC: Business as Usual)
Angela Wisher was a plumber who helped the Fifth Doctor investigate an invasion of Earth planned by the Tinghus in 2008. (AUDIO: Cuddlesome)
In 5000000000, Raffalo was a plumber on Platform One. She was killed by Cassandra O'Brien's metal spiders when she tried to reventilate the Face of Boe's tank. (TV: The End of the World)
Phil and Trev were existential plumbers. (AUDIO: A Perfect World)