What is the purpose of hydrant metering or flow testing before large operations?

• A. To calibrate the pump engine.
• B. To determine available water supply and ensure the system can meet the anticipated demand.
• C. To clean the hydrant only.
• D. To determine water temperature.

Answer: (B)

Knowing how much water can be drawn from the supply is essential before a large operation. Hydrant metering or flow testing provides a practical check of what the water system can deliver, so you can be sure it can meet the anticipated demand. By using a flow meter and pressure gauges on a hydrant, you measure the flow rate (GPM) and the pressures with the system in use. This tells you the available water and the pressure you’ll have when multiple attack lines or relay pumpers are working, guiding you on how many pumps are needed, where to lay lines, and how to stage operations without exhausting the source or dropping pressures elsewhere. The test can also uncover restrictions or issues such as valve positions or clogged hydrants that would limit flow, allowing corrections before operations begin.