How many drainage fixture units (DFU) does a residential clothes washer require?

How many drainage fixture units (DFU) does a residential clothes washer require?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (B)

Drainage fixture units show how much drainage load a fixture adds to the system, which helps determine the proper pipe size, slope, and venting. A residential clothes washer is assigned two DFU in standard code tables. That two reflects the typical amount of drainage the washer requires during a drain cycle and ensures the branch and main drains are sized appropriately without over- or underestimating capacity. If you look at other fixtures, some have smaller DFU values, and others have larger ones, but for a normal home laundry setup, two DFU is the agreed guideline. Always check your local code edition, but for the exam context this is the expected value.

Drainage fixture units show how much drainage load a fixture adds to the system, which helps determine the proper pipe size, slope, and venting. A residential clothes washer is assigned two DFU in standard code tables. That two reflects the typical amount of drainage the washer requires during a drain cycle and ensures the branch and main drains are sized appropriately without over- or underestimating capacity. If you look at other fixtures, some have smaller DFU values, and others have larger ones, but for a normal home laundry setup, two DFU is the agreed guideline. Always check your local code edition, but for the exam context this is the expected value.