What is the purpose of backflow prevention in water systems?

• A. Increase pressure
• B. Reduce flow
• C. Improve taste
• D. Prevent contamination of the supply

Answer: (D)

Backflow prevention protects the drinking water supply from contamination when pressure differences cause water to flow backward through cross-connections. If downstream systems like irrigation lines, boilers, or chemical feeds create a situation where non-potable water could be drawn into the main pipes, a backflow preventer acts as a one-way barrier—often using devices such as check valves or air gaps—to stop any reverse flow. This keeps contaminants from entering the potable supply, which is the essential purpose. The other ideas—raising pressure, reducing flow, or improving taste—aren’t the primary goal of backflow prevention; its job is to keep the water supply itself clean and safe.