Which practice helps prevent groundwater contamination when mixing pesticides?

• A. Using an air gap or back-flow protection device to protect your water supply when you mix pesticides.
• B. Securing pesticide containers in the back of a vehicle to prevent spills.
• C. Mixing pesticides on an open soil surface.
• D. Not checking containers for damage.

Answer: (A)

Preventing backflow from the mixing site into the water supply is essential to stop groundwater contamination. Using an air gap or back-flow protection device creates a physical separation or a one-way barrier between the water source and the pesticide container, so pesticides cannot be siphoned or drawn back into the water line. This keeps potentially contaminated water from entering wells, springs, or the groundwater as you mix, which is a key way to protect clean water supplies. The other practices don’t address this risk: securing containers in a vehicle helps prevent spills during transport but doesn’t prevent backflow into the water system; mixing on an open soil surface increases the chance of spills and leaching into soil and water; and not checking containers for damage can lead to leaks, but it doesn’t stop backflow into the water supply during mixing.