How high should an inlet line be above the liquid level?

The correct choice indicates that the inlet line should be positioned 3 inches above the liquid level. This elevation is crucial for several reasons. Firstly, maintaining a specific distance between the inlet line and the liquid level helps prevent siphoning, which can lead to backflow or contamination of the system. Secondly, positioning the inlet line at this height helps ensure that the line remains clear of floats, sediment, or debris that may accumulate at the surface or bottom of the tank, which could obstruct flow or cause malfunctions in the system.

Additionally, this height serves to enhance the overall system efficiency, ensuring that the inlet is optimally placed for the collection of liquid while minimizing the potential for air entrapment or turbulence that could affect the system's performance. Proper inlet line placement is a vital aspect of maintaining effective operation within any closed fluid system, particularly in OSSF applications, where managing effluent flow is essential for system integrity and environmental compliance.