Interesting thing - history of word
The word "plumber" dates from the Roman Empire. The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes 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.
Źródło: https://en.wikipedia.org/wiki/Plumber
Connect new devices to the network of water and sewage
Plumbers deal with the installation of water and sewage networks in a new house or new block of flats to be put into use. Then connects the boiler water. It also happens that in the old blocks, there is one department of water and after several years of use of the building administrator decides to perform the second division of water, and by the way checks the patency of the sewage system. Carrying out such work is indeed a nuisance for the residents of the block, but it greatly increases the standard of their daily lives. After their performance will be able to eg. To connect an additional bathroom faucet. Sometimes the desire to connect new devices to the network plumbing associated with the need to perform some plumbing work.
Linceses for plumber
Years of training and/or experience are needed to become a skilled plumber; some jurisdictions also require that plumbers be licensed.
Some needed skills, interests, and values
Reading drawings, and specifications to determine layout of water supply, waste, and venting systems
Detecting faults in plumbing appliances and systems, and correctly diagnosing their causes
Installing, repairing and maintaining domestic, commercial, and industrial plumbing fixtures and systems
Locating and marking positions for pipe connections, passage holes, and fixtures in walls and floors
Measuring, cutting, bending, and threading pipes using hand and power tools or machines
Joining pipes and fittings together using soldering techniques, compression fittings, threaded fittings, and push-on fittings.
Testing pipes for leaks using air and water pressure gauges
Awareness of legal regulations and safety issues
Ensuring safety standards and build regulations are met.
United States
Each state and locality may have its own licensing and taxing schemes for plumbers. There is no federal law establishing licenses for plumbers.
United Kingdom
Plumbers in the United Kingdom are required to pass Level 2 and Level 3 vocational requirements of the City and Guilds of London Institute.
Źródło: https://en.wikipedia.org/wiki/Plumber#Plumbing_activities