Massachusetts Plumbers Journeyman Practice Exam

What is the minimum branch waste size required for a kitchen sink waste according to specified guidelines?

1. 1 inch

2. 1 ¼ inch

3. 1 ½ inch

4. 2 inches

The correct answer is: 1 ½ inch

The minimum branch waste size required for a kitchen sink waste is indeed 1 ½ inches, which aligns with commonly established plumbing codes and standards. This size is optimal for effectively handling the flow of wastewater from kitchen sinks, accommodating the volume generated by typical kitchen activities such as dishwashing and food preparation. Choosing a diameter of 1 ½ inches ensures sufficient drainage capacity to minimize the risk of clogs, which could occur with smaller pipes. It also balances the need for adequate waste removal while preventing excessive redundancy in pipe size, which could lead to increased costs and unnecessary complexity in plumbing systems. Smaller sizes, such as 1 inch or 1 ¼ inch, may not provide adequate flow rates necessary for a kitchen sink's demands, while a 2-inch pipe could be unnecessarily large for residential kitchen applications where standard practices dictate a 1 ½ inch size. Hence, this size represents a practical and widely accepted standard in plumbing.