Pro Plumbers

Cast iron and ductile iron pipe was long a lower-cost alternative to copper, before the advent of durable plastic materials but special non-conductive fittings must be used where transitions are to be made to other metallic pipes, except for terminal fittings, in order to avoid corrosion owing to electrochemical reactions between dissimilar metals (see galvanic cell).[17]
The word "plumber" dates from the Roman Empire.[3] The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes[4] and some were also covered with lead, lead was also used for piping and for making baths.[5] In medieval times anyone who worked with lead was referred to as a plumber as can be seen from an extract of workmen fixing a roof in Westminster Palace and were referred to as plumbers "To Gilbert de Westminster, plumber, working about the roof of the pantry of the little hall, covering it with lead, and about various defects in the roof of the little hall".[6] Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber.