What is the approximate rate of discharge from a single "fixture unit"?

A single fixture unit is a standardized measure used in plumbing to quantify the probable demand on a plumbing system. It helps in designing a system to determine the necessary pipe sizes and water supply requirements based on the expected usage.

The rate of discharge from one fixture unit is generally accepted to be approximately 1 cubic foot per hour. This standardization allows for accurate calculations when designing plumbing systems to ensure that they can handle the peak flows expected during operation. Using this value, plumbers can effectively calculate the total demand on a plumbing system when multiple fixtures are involved.

In this case, while other rates of discharge might seem plausible, they do not align with the established standard for a single fixture unit. The choice of 1 cubic foot per hour is widely recognized in plumbing codes and engineering practices, making it the correct answer for this question.