What is the best method of backflow control?

Air gap separation is considered the best method of backflow control because it provides a physical barrier between the source of contamination and the potable water supply. An air gap is created by ensuring a vertical distance between the outlet of a water supply and the flood level of the receptacle it is discharging into. This method effectively prevents backflow by using gravity and the physical separation of fluids, making it one of the most reliable ways to protect drinking water from contamination.

The reason air gap separation is favored is that it eliminates the possibility of any siphoning action, as there is no direct connection between the potentially contaminated water and the clean water supply. It is simple, cost-effective, and requires no mechanical components, which can fail over time.

Other methods, such as vacuum breakers and backflow preventers, while effective, have limitations and can be subject to mechanical failure or require regular maintenance to ensure they function correctly. Barometric loops, another method, are generally more complex and require specific conditions to be effective. Thus, air gap separation stands out as the most dependable and straightforward solution for preventing backflow.