What device consists of one-way check valves and is designed to keep water or contaminants from re-entering the public water supply?

What device consists of one-way check valves and is designed to keep water or contaminants from re-entering the public water supply?

• A. Back flow preventer
• B. Check valve
• C. Pressure regulator
• D. Air gap

Answer: (A)

The main idea is protecting the public water supply from contamination by stopping any reverse flow. A backflow preventer is designed so water can only move away from the source toward the building, and it uses one-way check valves to block flow if pressure on the supply side falls or a downstream source tries to push water back. In effect, it creates a barrier that prevents contaminated water from re-entering the distribution system. Some designs stack multiple check valves and include a relief mechanism to guard against both backpressure and backsiphonage, providing reliable protection where cross-connections could occur.

The main idea is protecting the public water supply from contamination by stopping any reverse flow. A backflow preventer is designed so water can only move away from the source toward the building, and it uses one-way check valves to block flow if pressure on the supply side falls or a downstream source tries to push water back. In effect, it creates a barrier that prevents contaminated water from re-entering the distribution system. Some designs stack multiple check valves and include a relief mechanism to guard against both backpressure and backsiphonage, providing reliable protection where cross-connections could occur.