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
They can be carried out on behalf of local authorities, if any part of the village needs to be connected to the municipal sewer system or the village was flooded by torrential rains.
At the same time the hydraulic assistance can apply the owners of private houses, in which there have been some failures.Depending on the type of failure, they can order the execution of hydraulic works in normal mode, or call the emergency hydraulic.
While minor work will be done by appointment convenient for the homeowner term..