What is the size of the building drain in the notes?

What is the size of the building drain in the notes?

• A. 4 inches
• B. 3 inches
• C. 5 inches
• D. 6 inches

Answer: (C)

The size of a building drain is chosen to handle the total wastewater load from all fixtures in the building and to keep the flow moving so solids don’t settle and cause clogs. In the notes used for this course, the example sizing calls for a larger-diameter drain to reliably carry the expected flow from a typical building. That’s why the correct choice is the larger option: it meets the anticipated fixture load and provides adequate capacity. Using a smaller diameter would be undersized for the assumed load, increasing the risk of backups and poor drainage. When sizing, you rely on the fixture units and the flow requirements in the notes or code tables to pick a diameter that ensures a self-cleansing velocity and sufficient capacity.

The size of a building drain is chosen to handle the total wastewater load from all fixtures in the building and to keep the flow moving so solids don’t settle and cause clogs. In the notes used for this course, the example sizing calls for a larger-diameter drain to reliably carry the expected flow from a typical building. That’s why the correct choice is the larger option: it meets the anticipated fixture load and provides adequate capacity. Using a smaller diameter would be undersized for the assumed load, increasing the risk of backups and poor drainage. When sizing, you rely on the fixture units and the flow requirements in the notes or code tables to pick a diameter that ensures a self-cleansing velocity and sufficient capacity.