Which situation indicates the need for backflow-prevention devices?

• A. The system is a simple, isolated potable water line with no cross-connections.
• B. There is a potential contamination risk due to a cross-connection.
• C. Backflow-prevention devices are never needed.
• D. All fixtures are on the same supply with no risk.

Answer: (B)

Backflow prevention is all about stopping contaminants from being drawn back into the clean drinking water when pressure changes or a connection exists between the potable supply and a non-potable source. The situation that indicates a need is when there is a potential contamination risk due to a cross-connection. A cross-connection is any link between the potable system and non-potable substances, such as chemicals, fertilizers, or wastewater, that could push back into the water supply if pressure drops or if a higher-pressure non-potable source pushes into the line. In that scenario, installing a backflow-prevention device creates a barrier so reverse flow can’t occur, protecting the potable supply. If the system is simple, isolated, and there’s no cross-connection or contamination risk, a backflow device isn’t required.