Which of the following is a potential hazard involving water supply and plumbing systems?

• A. Non-potable water contacting food
• B. Regional hazards (radiological hazards)
• C. Cross-connections/backflow between potable and non-potable sources
• D. Ice from potable water

Answer: (C)

The main concept here is preventing backflow and cross-connections in the water supply to avoid contaminating potable water through the plumbing system. When potable water is linked to non‑potable sources in a way that allows backflow, pressure changes can siphon contaminants into the drinking water line. This poses a serious risk to food safety because contaminated water can reach equipment, surfaces, and food via pipelines, valves, hoses, or ice machines. Mitigation focuses on preventing cross-connections and backflow with proper design and maintenance—air gaps, backflow prevention devices, proper valve alignment, and regular testing and inspection to ensure the potable supply remains hydraulically separated from non-potable sources. While other hazards like non-potable water contacting food or radiological regional hazards are concerns in broader risk analysis, the hazard that directly arises from the plumbing system itself is cross-connections/backflow between potable and non-potable sources.