A plumber was a worker who fixed plumbing.
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)
Angela Wisher was a plumber who helped the Fifth Doctor investigate an invasion of Earth planned by the Tinghus in 2008. (AUDIO: Cuddlesome)
Phil and Trev were existential plumbers. (AUDIO: A Perfect World)