What provides the best level of protection in all backflow situations?

An air gap is the best level of protection in all backflow situations because it creates a physical separation between the potable water supply and any potential contaminants. By establishing a vertical distance between the water outlet and the flood level of the fixture, an air gap effectively prevents any backflow of contaminated water into the clean water supply. This method is highly reliable because it does not rely on mechanical components, which can fail over time.

In contrast, other devices like backflow preventers, check valves, and pressure regulators may help mitigate backflow risks, but they can sometimes malfunction or be subject to failure due to wear or blockage. An air gap is a passive, straightforward solution that does not impose any risk of failure, making it the most robust option for maintaining the integrity of water systems against contamination.