What device should be used when field lines are above the operating water level to prevent backflow?

The check valve is the appropriate device to use when field lines are situated above the operating water level to prevent backflow. This type of valve is designed to allow fluid to flow in only one direction, effectively preventing the reverse flow of wastewater or effluent. In scenarios where the field lines are elevated, there is a risk of the fluid traveling back into the system due to hydrostatic pressure or backpressure conditions.

By installing a check valve, you ensure that any potential backflow is stopped, allowing the system to maintain its integrity and function properly. This is crucial in septic systems, where keeping wastewater contained within the intended flow path is essential for both efficiency and environmental safety. The check valve's ability to prevent backflow safeguards against possible contamination of the septic system and surrounding areas, thereby adhering to health regulations and maintaining operational effectiveness.