What is the minimum outlet diameter for lavatories as per plumbing standards?

The minimum outlet diameter for lavatories, as established by plumbing standards, is 1 1/4 inch. This size is important to ensure adequate drainage and to prevent clogs that can occur with smaller diameters. A 1 1/4 inch outlet allows for a sufficient flow rate to accommodate the typical usage of a lavatory, which includes activities like washing hands and face, while also effectively handling the waste and water runoff.

Sizing the outlet correctly is crucial to maintaining proper plumbing function and to comply with building codes. A larger outlet, such as 1 1/2 inches or 2 inches, may be appropriate for different fixtures, but for standard lavatories, the 1 1/4 inch is the minimum required to balance functionality and code compliance without leading to unnecessary complications or higher material costs.