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 the potable supply in case of pressure fluctuation or pump back-pressure
• B. To reduce noise
• C. To improve detergents mixing
• D. To increase water pressure

Answer: (A)

Backflow prevention on a cold water feed is about protecting the drinking water supply. When a dishwasher or washing machine is filling, or if the system experiences pressure changes or pump back-pressure, water could be pulled backward into the potable line. A backflow preventer creates a barrier that stops that reverse flow, preventing non-potable water, detergents, or contaminants from entering the supply.

This device isn’t about reducing noise, improving how detergents mix, or increasing water pressure. Its job is safety—keeping the clean water system free from reverse flow hazards.