Which of the following is NOT a method for backflow prevention?

A pump system does not serve as a method for backflow prevention. Backflow prevention devices are specifically designed to prevent the reverse flow of water, which can cause contamination within the potable water supply.

An air gap is a physical separation between the water source and the receiving vessel, ensuring that contaminated water cannot flow back into the clean water supply. It is one of the most effective methods because it provides a clear, unobstructed distance that contaminants cannot cross.

Check valves are mechanical devices that allow flow in one direction and prevent backflow. Their design ensures that if pressure on the downstream side decreases, the valve closes and blocks any reverse flow.

Reduced pressure zone devices are advanced backflow prevention mechanisms that maintain a lower pressure in the area between two shutoff valves, creating a barrier to backflow. This system is used in situations where the risk of contamination is high.

Thus, the inclusion of a pump system in this context is not appropriate as a backflow prevention method, as a pump is typically used to move water rather than prevent backflow.