What is the minimum diameter of waste piping for a bathtub?

The minimum diameter of waste piping for a bathtub is specified as 1 1/2 inches in the Massachusetts Plumbing Code. This size is deemed necessary to efficiently handle the drainage and ensure that there is minimal risk of clogging due to soap residue, hair, and other debris that typically accumulate in bathtub waste lines.

Using a diameter smaller than 1 1/2 inches could lead to slower drainage and a higher likelihood of blockages, which could compromise the plumbing system's performance and create potential sanitary issues. Additionally, the standardization of this size helps maintain consistency in plumbing practices and ensures that installations are up to code, promoting overall safety and functionality in residential and commercial plumbing systems.