What is the typical trap size for a kitchen sink in a residence?

The typical trap size for a kitchen sink in a residence is 1 1/2 inches. This size is standard in most plumbing codes and practices, as it provides an adequate flow rate for the wastewater produced in kitchen sinks while preventing the risk of clogs. A 1 1/2-inch trap effectively minimizes the potential for backflow, which can occur with larger diameter traps that allow for a slower drainage rate under certain conditions. Additionally, this size strikes a balance between ease of installation and maintaining effective drainage, aligning with common residential plumbing configurations.

Other sizes, such as 1-inch, may be used in smaller fixtures but are generally not sufficient for a kitchen sink, where larger amounts of liquid and solids are present. A 2-inch or 3-inch trap, while potentially usable, is typically reserved for fixtures that generate a larger volume of discharge, such as commercial kitchens, and may introduce complications like requiring larger drains or having a less effective water seal in a residential context. Thus, for a standard kitchen sink installation, 1 1/2 inches remains the ideal choice.