What is gpm and where is it used?

• A. Gallons per minute; used to measure soil moisture.
• B. Gallons per minute; used to rate flow rates of fixtures and irrigation controllers.
• C. Grams per meter; used to measure water pressure.
• D. Global pressure measure; used in pipeline design.

Answer: (B)

GPM stands for gallons per minute, a unit that describes flow rate—the amount of water moving past a point each minute. In irrigation and plumbing, gpm is used to rate how much water a fixture, nozzle, valve, or irrigation controller can deliver. This helps you size pipes and controllers, estimate how long a zone must run to meet a plant’s water needs, and ensure the total flow doesn’t exceed the system’s capacity. It’s not used to measure soil moisture (which is about water content in the soil) or water pressure (which is measured in psi or kPa), and grams per meter isn’t a standard measure for water flow.