Wikipedia about common types of valves
Valves vary widely in form and application. Sizes typically range from 0.1 mm to 60 cm. Special valves can have a diameter exceeding 5 meters.
Valve costs range from simple inexpensive disposable valves to specialized valves which cost thousands of US dollars per inch of the diameter of the valve.
Disposable valves may be found in common household items including mini-pump dispensers and aerosol cans.
A common use of the term valve refers to the poppet valves found in the vast majority of modern internal combustion engines such as those in most fossil fuel powered vehicles which are used to control the intake of the fuel-air mixture and allow exhaust gas venting.
Wikipedia about plumbing systems
The major categories of plumbing systems or subsystems are:
potable cold and hot tap water supply
plumbing drainage venting
sewage systems and septic systems with or without hot water heat recycling and graywater recovery and treatment systems
Rainwater, surface, and subsurface water drainage
fuel gas piping
hydronics, i.e. heating and cooling systems utilizing water to transport thermal energy, as in district heating systems, like for example the New York City steam system.
Repair minor faults hydraulic
Malfunctions related to the plumbing is a real nightmare for the residents of the building. There are often such failures, which for a long time to hinder the normal functioning and cause many other problems, but some of them are too small and can be quickly repaired. It is important, however, that even the smallest failure to call the appropriate professionals, because even if something on the surface it seems to us trivial, inadequately repaired, can result in a much higher failure and pretty large problems. Repair small defects do not pay much, and good specialist will deal with it quickly and professionally. It is so much simpler, cheaper and better solution than self-repair.