A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways.
Valves are technically fittings, but are usually discussed as a separate category.
In an open valve, fluid flows in a direction from higher pressure to lower pressure.The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll. The simplest, and very ancient, valve is simply a freely hinged flap which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction. Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems. Źródło: https://en.wikipedia.org/wiki/Valve
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.
It will be able not only to assume, but also seal the counter in such a way that the reading will be error.
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.
Besides a good plumber can recommend the purchase of such sanitary facilities that allow you to save water..