The simplest way to prevent back-siphoning is to keep the discharge end of the water supply line at least 12 inches below the surface of the pesticide solution in the spray tank.

• A. True
• B. False
• C. Not recommended
• D. Depends on the pesticide

Answer: (B)

Preventing back-siphonage means stopping a path for liquid from the spray tank to be drawn back into the water supply when pressure in the system fluctuates. The simplest protection is to create an air gap or use a backflow prevention device, which means the discharge end of the water supply line should not be submerged in the tank liquid. Keeping the line end below the surface (such as 12 inches under) actually facilitates siphoning rather than preventing it. Instead, keep the hose end above the liquid level or install a proper anti-siphon device so there’s a gap that stops contaminated spray from entering the water supply.