In plumbing, what unit is used to measure a fixture's flow rate?

The unit used to measure a fixture's flow rate in plumbing is gallons per minute (GPM). This measurement is essential in evaluating how efficiently a plumbing fixture operates, particularly in ensuring that it meets the necessary standards for water usage. GPM indicates how many gallons of water pass through a fixture in one minute, making it a practical and widely recognized metric in the plumbing industry.

Using gallons per minute allows plumbers and engineers to assess the performance of faucets, showers, and toilets, enabling them to design systems that meet both user needs and regulatory requirements. It is also helpful for estimating water usage and costs in residential and commercial settings.

Other measurements such as liters per hour, cubic feet per second, and milliliters per minute do exist, but they are not commonly used in plumbing in the same way that gallons per minute is. GPM is the industry standard that facilitates consistent communication and regulation in the field.