Which device is typically used to prevent backflow in water supply systems?

The device that is typically used to prevent backflow in water supply systems is a backflow preventer. A backflow preventer is specifically designed to protect potable water supplies from contamination or pollution that can occur when water flows backward into the system. This device operates by creating a physical barrier that stops the reverse flow of water, ensuring that any contaminants present in the non-potable water cannot enter the drinking water supply. It employs various mechanisms, including check valves and atmospheric vacuum breakers, to achieve this critical function.

While an air gap can also prevent backflow by maintaining a physical separation between the water supply and potential contaminants, it is not a mechanical device like a backflow preventer. Flow restrictors are used to limit the amount of water flow but do not specifically address backflow issues, and pressure gauges measure water pressure within a system but play no role in preventing backflow. Therefore, the backflow preventer stands out as the essential device for safeguarding water supply systems from backflow risks.