What plumbing fixture requires a backflow preventer to ensure safety?

A hose bib, or outdoor faucet, requires a backflow preventer to ensure safety because it is directly exposed to outdoor elements and is often used for watering plants, washing cars, or filling pools. When a hose is connected to the bib, there’s a potential for contaminated water from those activities to siphon back into the drinking water supply. A backflow preventer is specifically designed to prevent this reverse flow of water, protecting the potable water supply from contamination due to back pressure or back siphonage.

In contrast, while toilets, sinks, and showers are important fixtures in plumbing systems, they are typically installed in a way that minimizes contamination risks from water backflow. They often include integral features that help prevent backflow, such as trap seals and air gaps, making backflow preventers less critical in those applications. This distinction highlights why a hose bib is particularly vulnerable and in need of a backflow preventer to safeguard public health.