The Correct Answer and Explanation is:
The correct answer is vacuum breaker.
The question addresses a crucial aspect of plumbing safety: preventing the contamination of the potable (drinkable) water supply. A threaded faucet, like an outdoor hose bibb or a utility sink faucet, allows for the connection of a hose. This common setup can create a significant health hazard if not properly protected.
The danger arises from a situation called a cross connection, which is any direct physical link between the clean water system and a potential source of contamination. For example, if the end of a garden hose attached to a faucet is left submerged in a swimming pool, a puddle of stagnant water, or a bucket of pesticides, a cross connection is formed.
If a sudden drop in pressure occurs in the main water supply (due to a water main break or a nearby fire hydrant being used), a vacuum can be created in the plumbing. This phenomenon, known as backflow or backsiphonage, can suck the contaminated water from the pool or bucket back through the hose, into the faucet, and into the building’s drinking water pipes. This can lead to widespread illness.
To prevent this, an approved backflow prevention device is legally required on such connections. The correct device for a threaded faucet is a vacuum breaker. A hose bibb vacuum breaker (HBVB) is a simple, inexpensive attachment that screws directly onto the faucet’s threads. It contains a valve that allows water to flow out but seals shut and opens to the atmosphere if a vacuum is detected. This lets air into the line, which breaks the siphon and prevents any contaminated water from being drawn back into the plumbing system.
Therefore, while a cross connection is the problem to be avoided, a vacuum breaker is the approved safety device that solves it.
