What is the function of a hose bib in plumbing systems?

The primary function of a hose bib, also known as a spigot or sillcock, is to provide an outdoor water supply connection. This allows homeowners to conveniently access water outside their residences for various tasks such as watering plants, washing cars, filling pools, and general outdoor cleaning. Hose bibs are typically located on exterior walls and are designed to enable a standard garden hose to be easily connected or disconnected.

While other options may relate to functions that occur in plumbing systems, they do not directly define the main purpose of a hose bib. For instance, winterizing a water supply (option A) involves taking additional steps like draining and insulating pipes to prevent freezing, which is not the primary role of the hose bib itself. Preventing backpressure (option C) typically pertains to devices specifically designed for backflow prevention and is not a function of the hose bib. Connecting to an irrigation system (option D) might be a use of a hose bib, but it is not the overall function, as hose bibs are used for a variety of outdoor water needs beyond just irrigation. Thus, the correct emphasis here is on its role as an essential outdoor water source.