What is the purpose of a hose bib with an anti-siphon mechanism, and where should it be installed?

• A. To prevent backflow from a garden hose into the cold water supply; installed on external outlets with anti-siphon devices
• B. To increase the water pressure to the hose
• C. To insulate the hose bib
• D. To filter the incoming water

Answer: (A)

Backflow protection is the key idea. When a hose is attached to an outdoor faucet, pressure changes or a leak in irrigation lines can cause water to be siphoned back into the cold water supply, risking contamination of the potable system. An anti-siphon hose bib includes a vacuum breaker that intercepts this potential backflow by allowing air into the line and blocking reverse flow. This keeps any dirty or contaminated water from entering the home’s water supply.

Because of the backflow risk, this device belongs on exterior outlets that are used with hoses. It’s specifically designed for outdoor faucets to protect the potable water system when hoses are connected. It’s not intended to increase pressure, insulate, or filter the water.