A drainage fixture unit (dfu) is equivalent to how many gallons of water flow?

A drainage fixture unit (dfu) is a standard measurement used in plumbing to quantify the probable discharge into the drainage system from various plumbing fixtures. It is essential for designing and sizing drainage systems in buildings. The value of 7.5 gallons per minute is widely recognized because it reflects a typical drainage capacity that can be expected from a range of fixtures. This figure provides a consistent basis for engineers and designers to calculate the load on drainage systems and ensures that they can adequately handle the expected flow without risk of blockage or overflow.

Understanding this value is crucial for maintaining effective plumbing throughout a building, as it allows for proper sizing and installation of pipes, ensuring an efficient drainage system under varying conditions. The other options may not align with the generally accepted standard of 7.5 gallons per minute, which is why this choice is regarded as the correct answer in the context of drainage fixture units.