One who furnishes, fits, and repairs lead, iron, glass or plastic pipes, and other apparatus for the conveyance of water, gas or drainage; originally, one who did piping for waste water, as distinct from a pipe fitter, who dealt only with fresh water
A plumber is a person whose job is to connect and repair things such as water and drainage pipes, baths, and toilets. someone whose job is to repair water pipes, baths, toilets etc (plommier , from plumbarius, from plumbus ; because water pipes were originally made of lead)