Where should residual pressure be measured in a water distribution system?

Residual pressure in a water distribution system should be measured at the nearest hydrant upstream from the flowing hydrant because this location allows for the assessment of the pressure available to consumers and firefighting services while considering the system's operational conditions.

When hydrants are opened, water flows from the system, which can cause pressure drops due to the resistance in the pipes. Measuring the residual pressure upstream provides a more accurate representation of the water pressure that is actually available to users during high-demand scenarios, such as firefighting, where accurate pressure readings are critical.

The choice to measure at this site takes into account potential losses from friction and other factors that occur as water travels through the system. Monitoring at the storage tank outlet or pump discharge would not accurately reflect the pressure available to end users during flow conditions since these locations may not account for the entire distribution system's resistance. Similarly, measuring at the treatment facility focuses on supply rather than distribution dynamics and pressure availability.

Therefore, measuring upstream from the flowing hydrant provides the essential information needed for effective management and operation of the water distribution system.