What is the term for water pressure in a main or in a container that is measured by a gauge?

The term for water pressure in a main or in a container that is measured by a gauge is 'gauge pressure.' This refers specifically to the pressure relative to atmospheric pressure, meaning it indicates how much pressure exists above or below the atmospheric baseline.

Gauge pressure is what is typically displayed on pressure gauges, which measure only the pressure exerted by the water in the system or container, not accounting for the external atmospheric pressure. For instance, if a gauge reads zero, it means that the pressure inside the system equals atmospheric pressure. Thus, gauge pressure is crucial for assessing the performance and safety of water distribution systems, ensuring that they operate within designated pressure ranges.

In contrast, other terms, while related to pressure, refer to different concepts. Static pressure pertains to pressure when the fluid is at rest. Atmospheric pressure is the pressure exerted by the weight of the atmosphere at a given location. Absolute pressure refers to the total pressure, including both gauge pressure and atmospheric pressure. Understanding these distinctions is essential for interpreting pressure readings accurately in water distribution systems.