Which of the following is not a method used for Backflow prevention?

The swing connection is not recognized as a legitimate method for backflow prevention. Backflow prevention methods are specifically designed devices or configurations that effectively stop the reverse flow of water, which can lead to contamination of potable water supplies.

An air gap functions by allowing a vertical space between the water supply and the potential contamination point, creating a physical barrier that prevents backflow. Similarly, double check valves are devices designed to ensure that if one valve fails, the backup valve still protects the water supply from backflow. Reduced pressure zone (RPZ) assemblies are sophisticated devices that use differential pressure to prevent backflow under varying conditions, making them highly effective in protecting water systems.

In contrast, a swing connection does not serve any purpose as a backflow prevention method. It does not provide the necessary physical or mechanical barriers required to stop contaminated water from flowing back into the supply system. Recognizing the appropriate methods for backflow prevention is crucial for maintaining the integrity of water systems.