What is the minimum requirement for an air break in plumbing?

The minimum requirement for an air break in plumbing is established to prevent backflow and contamination of potable water supplies. The correct choice specifies that the air break must be one pipe diameter or at least 1 inch from a drain. This separation creates a physical barrier that prevents any potential siphoning action from occurring, thus ensuring that wastewater does not enter the drinking water supply.

By adhering to this standard, it helps maintain the integrity of plumbing systems and protects public health. The mention of "one pipe diameter" means that the distance is proportional to the size of the pipe, ensuring adequacy across various pipe sizes. The additional stipulation that it must be at least 1 inch ensures a baseline safety margin, particularly in smaller diameter systems.

The other options would either not provide a sufficient air gap or suggest a measurement that could lead to a risk of contamination, which is why they do not meet the established requirements for an effective air break. The correct standard reflects the best practices in plumbing to safeguard water quality.