What is the purpose of an air gap or back-siphoning device in pesticide application systems?

• A. Prevent backflow into the water supply
• B. Improve spraying efficiency
• C. Change the color of the water
• D. Reduce evaporation

Answer: (A)

Preventing contamination of the water supply by stopping any liquid from flowing backward into the potable water line. When a sprayer is used, changes in pressure or backward flow could pull pesticide-containing water back into the drinking-water system. An air gap creates a physical separation between the water outlet and the spray solution, so a siphon can’t form and pull liquid back into the supply. A back-siphon or one-way device serves the same purpose by preventing flow from returning to the water line. This protection is why the option that describes preventing backflow into the water supply is correct. It doesn’t affect spraying efficiency, color of the water, or evaporation.