International Residential Code (IRC) Plumbing Test 2025 – 400 Free Practice Questions to Pass the Exam

For a cleanout to facilitate proper cleaning, it must open in line with the flow of the drainage line. This design ensures that when a cleaning tool, such as a snake, is inserted through the cleanout, it can easily navigate through the pipe along the same path as the waste water flows. This alignment allows for unobstructed access to the entire drainage system, making it more efficient to clear blockages and perform maintenance.

Opening a cleanout in line with the flow also helps prevent potential backflow of waste during cleaning operations, which not only aids in maintaining hygiene but also ensures that the cleaning process is more effective. In contrast, options suggesting that a cleanout should open against the flow, perpendicular to the flow, or in a random direction would hinder the effort to effectively remove blockages and complicate access to the drainage system, thus making maintenance more difficult.