What is the minimum outside diameter for a trap serving the combined discharge from a dishwasher and a two-compartment sink with a food-waste disposer?

• A. 1 inch
• B. 1 ½ inches
• C. 2 inches
• D. 2 ½ inches

Answer: (B)

The minimum outside diameter for a trap serving the combined discharge from a dishwasher and a two-compartment sink with a food-waste disposer is established to ensure that the drainage system can adequately handle the waste and prevent clogs. A trap with a diameter of 1 ½ inches is specified because it provides sufficient capacity for the flow expected from both the dishwasher and the sink, especially when a food-waste disposer is included.

The 1 ½ inch diameter allows for proper venting and minimizes the risk of backflow or buildup of solid waste, which can occur if the diameter is too small. Ensuring that this dimension meets code requirements is essential for preventing plumbing issues and ensuring proper drainage. Larger diameters, while they may enhance flow capacity, are not the minimum requirement established by the plumbing codes for the specific application in question, meaning they are not necessary in this context.

Therefore, utilizing a 1 ½ inch trap conforms with recognized plumbing standards for such installations and effectively manages the discharge from the kitchen appliances involved.