The scope of work of hydraulic
The scope of work includes running small hydraulic repair and counteract the negative effects of large hydraulic failure including, for example, one part of the city. Then in his work co-operate with the fire department, which deals with pumping water from flooded premises or the flooded area of the city. In such a situation, plumbers, first assess the damage done plumbing, and then deal with their valuation and inform the owners of the premises or the city authorities of its findings. Only on this basis can take care of carrying out the necessary repairs. Normally plumbers work from Monday to Friday or Saturday, but in emergency situations may proceed to carry out their work even on Sundays.
About license
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
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