What is the minimum waste pipe size for a Type I interceptor?

The minimum waste pipe size for a Type I interceptor is 4 inches. This standard is set to ensure that the interceptor can effectively handle the anticipated flow rates and solids present in the wastewater, particularly in commercial kitchens where fats, oils, and grease (FOG) are prevalent. A larger pipe size helps prevent clogs and ensures efficient drainage, which is critical for maintaining plumbing health and adherence to code requirements.

When a smaller pipe is used, such as 2 inches or 3 inches, the system may struggle to manage the volume and characteristics of the waste, leading to potential backups or reductions in interceptor efficiency. A 6-inch pipe, while capable, exceeds the minimum requirement and is typically not necessary for most applications, which could lead to increased material costs without additional functional benefits. Therefore, the 4-inch pipe size strikes the appropriate balance for Type I interceptors as per the Omaha Plumbing Code.