What is a plumbing fixture's water supply fixture unit based on?

What is a plumbing fixture's water supply fixture unit based on?

• A. Fixture flow rate when the fixture is used
• B. Average time water is actually flowing when a fixture is being used
• C. Frequency with which the fixture is used
• D. Type of building where the fixture is installed

Answer: (A)

A plumbing fixture’s water supply fixture unit reflects the fixture’s instantaneous demand on the water system—the flow rate that occurs while the fixture is in use. This basis lets designers convert a variety of fixtures into a common unit so they can be summed to size and design the water supply piping, ensuring adequate pressure and flow during peak usage. It isn’t determined by how long water runs, how often the fixture is used, or the type of building; those factors influence overall demand through other design considerations, but the fixture unit value itself comes from the actual flow rate when the fixture operates.

A plumbing fixture’s water supply fixture unit reflects the fixture’s instantaneous demand on the water system—the flow rate that occurs while the fixture is in use. This basis lets designers convert a variety of fixtures into a common unit so they can be summed to size and design the water supply piping, ensuring adequate pressure and flow during peak usage. It isn’t determined by how long water runs, how often the fixture is used, or the type of building; those factors influence overall demand through other design considerations, but the fixture unit value itself comes from the actual flow rate when the fixture operates.