What size cleanout is provided for piping up to 4 inches?

The correct answer is that the cleanout provided for piping up to 4 inches should be the same size as the pipe. This approach ensures that there is sufficient access for cleaning and maintenance of the plumbing system without any restrictions that could potentially hinder flow or make the cleaning process less effective.

Using the same size as the pipe allows for a direct and unobstructed path, which is important when performing maintenance work such as snaking out a clog or conducting inspections. When cleanouts are appropriately sized, they promote easier access to the piping system's interior, enabling effective removal of blockages and facilitating any necessary repairs.

Choosing a different size, such as making the cleanout larger or smaller than the pipe, could complicate maintenance tasks, leading to inefficiencies and potentially requiring more specialized equipment to navigate changes in diameter. Thus, maintaining consistency in size between cleanouts and the piping they service is a best practice in plumbing design.