Journeyman plumber: Once the requirements of an apprenticeship are fulfilled, plumbers can apply for a journeyman license. Many workers in the plumbing industry are journeymen. Obtaining a journeyman's license requires a fee and the successful passing of an exam. Licenses vary by state, although not all areas require journeymen to be licensed. Instead, the amount of work they are able to perform is limited.
"lead hung on a string to show the vertical line," early 14c., from Old French *plombe, plomee "sounding lead," and directly from Late Latin *plumba, originally plural of Latin plumbum "lead (the metal), lead ball; pipe; pencil," a word of unknown origin, related to Greek molybdos "lead" (dialectal bolimos) and perhaps from an extinct Mediterranean language, perhaps Iberian.
Despite the Romans' common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, the Roman water had so much calcium in it that a layer of plaque prevented the water contacting the lead itself. What often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water. This was an unfortunate result of lead being used in cookware and as an additive to processed food and drink, for example as a preservative in wine. Roman lead pipe inscriptions provided information on the owner to prevent water theft.
Those who attempted to bring plumbing indoors faced technical as well as attitudinal challenges. Decisions on how wastewater was removed required as much concern as those made to ensure an adequate water supply. But equally vexing was the prevailing miasma theory of disease, which held that illnesses stemmed from "bad air" that was readily identifiable by its offensive odor. This led to a distrust of early indoor plumbing that tended to leak and a deadly fear of the sewer gas that accompanied the leaks. It is no wonder then that many individuals maintained a strong belief that elimination was best taken care of out of doors.