A hose bibb (outdoor faucet) is used to attach a hose for cleaning. What device is commonly installed to prevent backflow at that connection?

解析

A hose connection is a common backflow risk, so an approved backflow prevention device such as a vacuum breaker is installed to stop contaminated water from being siphoned back into the potable system. When a permanent air gap is not feasible, a mechanical device like a vacuum breaker is the accepted protection. A grease trap intercepts fats leaving the waste line, a floor drain carries water away, and a pressure gauge only reports pressure — none of them blocks reverse flow into the supply.