When sizing a water distribution system, what is the water-supply fixture unit value for a tank-type water closet?

• A. 1.5
• B. 2.2
• C. 3.0
• D. 4.5

Answer: (B)

In the context of sizing a water distribution system, the water-supply fixture unit value is crucial for determining the demand placed on the system by different fixtures. For a tank-type water closet, the water-supply fixture unit value is 2.2. This value represents the average demand for water as it correlates with the expected usage during peak times, factoring in both the frequency of flushes and the volume of water used per flush.

The value of 2.2 takes into account that tank-type toilets typically use around 1.6 gallons per flush, which fits within the guidelines set forth by plumbing codes that design water supply systems to accommodate typical fixture demands. This uniform assessment helps ensure that the installed plumbing can handle expected loads without risking low pressure or inadequate supply during peak usage periods.

Therefore, the significance of this value becomes apparent when designing a water distribution system that is efficient and capable of meeting the needs of its users while adhering to plumbing standards.