Which component is used to prevent backflow where required in a cold water branch circuit?

• A. Non-return valve
• B. Service valve
• C. Branch isolation valve
• D. Flexible hose

Answer: (A)

Preventing backflow in a cold water branch relies on a one-way valve that blocks reverse flow. A non-return valve, or check valve, is designed to allow water to move in the intended direction but automatically closes if pressure reverses, preventing contaminated water from flowing back toward the supply. This protection is crucial in branches where pressure variations or connections to other systems could pull water backward.

A service valve is for isolating the supply for servicing, not for stopping backflow. A branch isolation valve only shuts off a portion of the line and doesn’t inherently prevent reverse flow. A flexible hose is just a connector and, by itself, doesn’t guarantee backflow protection unless it includes a built-in check valve.

So the non-return valve is the component that best prevents backflow in a cold water branch circuit.