How is a water supply system in a building typically pressurized?

A water supply system in a building is typically pressurized primarily through a pump or by utilizing municipal water pressure. When a system relies on pumps, it is designed to increase the pressure of water coming from the supply to ensure that it reaches all parts of the building effectively, especially in multi-story buildings where gravity alone may not suffice.

In many cases, municipal water systems are designed to maintain a specific pressure that allows water to flow efficiently to residential and commercial properties. This means that the plumbing is set up to take advantage of the pressure from the water mains supplied by the local water authority.

While gravity systems can work in some situations, especially in locations with adequate elevation, they are not as commonly used for pressurizing water supply systems in buildings as pumps or municipal pressure are. Valves play a role in controlling flow and pressure but do not directly pressurize the system. Similarly, expansion tanks are used to manage changes in water volume and pressure due to thermal expansion but are not the primary means of pressurizing the water system itself.