A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, sewage and drainage in plumbing systems.
Roman roofs used lead in conduits and drain pipes4 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.
This will allow precise determination of the amount of water used in the household and issuing the appropriate invoices, that will not in any way overpriced.At the same time plumber will be able to advise the owners of the visited household, how they can reduce the costs associated with the amount of water consumed.
Plumbing equipment includes devices often hidden behind walls or in utility spaces which are not seen by the general public.It includes water meters, pumps, expansion tanks, backflow preventers, water filters, UV sterilization lights, water softeners, water heaters, heat exchangers, gauges, and control systems. Specialized plumbing tools include pipe wrenches, flaring pliers, pipe vise, pipe bending machine, pipe cutter, dies and joining tools such as soldering torches and crimp tools. New tools have been developed to help plumbers fix problems more efficiently.
For example, plumbers use video cameras for inspections of hidden leaks or problems, they use hydro jets, and high pressure hydraulic pumps connected to steel cables for trench-less sewer line replacement.Źródło: https://en.wikipedia.org/wiki/Plumbing#Equipment_and_tools.