What is the appropriate size for a cleanout in relation to a drain pipe?

The appropriate size for a cleanout in relation to a drain pipe should correspond to the size of the drain pipe to ensure effective access for maintenance, cleaning, and inspection of the drainage system. In most plumbing codes and standards, a cleanout is typically required to match the size of the drainage line it serves, ensuring that any blockages can be adequately cleared and that the flow is not impeded.

When dealing with standard residential plumbing, a 4-inch cleanout is commonly used for 4-inch diameter drain pipes, which is a common size for main drainage lines in residential systems. This size provides a sufficient opening to allow for the insertion of augers or other cleaning tools to remove any obstructions.

While cleanout sizes may vary with different drainage systems and local codes, a 4-inch size is often viewed as a standard and effective choice for many typical applications. This alignment not only helps in maintaining the system's integrity but also ensures compliance with plumbing requirements.