What is the trap size for a service wall type sink?

The standard trap size for a service wall type sink is a 2-inch trap. A service sink, often used for utility purposes, requires a larger trap to accommodate higher wastewater flow and prevent blockages. The 2-inch size strikes a balance between effective drainage and the ability to handle a variety of waste types, which are typically encountered in service sinks.

A 1 1/2-inch trap would generally be too small for this application, potentially leading to drainage issues. A 3-inch or 4-inch trap, while capable of handling more volume, is not necessary for the average service sink and could make installation more cumbersome and expensive without providing proportional benefits. Thus, using a 2-inch trap ensures proper function and compliance with plumbing codes for this type of sink.