Why might a dishwasher or washing machine installation require a backflow prevention device on its cold water feed?

• A. To prevent backflow or siphoning of non-potable water into potable supply in case of pressure fluctuation or pump back-pressure
• B. To improve washing performance
• C. To regulate temperature
• D. To reduce water hardness

Answer: (A)

Backflow prevention is about protecting the clean water supply from contamination when an appliance could create a path for water to flow backward. If pressure in the cold-water line drops or a pump in the dishwasher or washer causes back-pressure, water from the appliance (which may carry detergents or other contaminants) could siphon back into the potable supply through a cross-connection. A backflow prevention device blocks that reverse flow, allowing water to flow only toward the appliance and keeping the drinking supply safe. This protection is specific to preventing contamination and isn’t about washing performance, temperature regulation, or water hardness.