What is an air break in a drainage system?

An air break in a drainage system refers to a specific piping arrangement where waste discharges below the flood level rim of a fixture. This design is critical for ensuring that any potential backflow is prevented, thereby safeguarding the potable water supply. The air gap created by this design allows air to break the siphon effect that could otherwise draw contaminated water back into the system, protecting against cross-contamination.

This arrangement is important because it maintains the separation between sewage and water supply systems, crucial for public health. In plumbing design, ensuring that waste systems have proper air breaks is a fundamental safety measure that adheres to plumbing codes and best practices.

The other options misinterpret the concept of an air break; for example, a direct discharge into a sewer line does not involve an air gap. An obstruction preventing drainage does not factually describe an air break, as it implies a blockage rather than a protective design element, and the vertical distance between two pipes could refer to various plumbing principles but doesn't specifically define what an air break entails.