What device is used to prevent well contamination during fertilizer mixing?

The anti-back-siphon device is essential in preventing well contamination during fertilizer mixing because it serves as a safeguard against the potential reverse flow of contaminated water back into the well system. This device ensures that when water is being drawn from the well for mixing, any sudden changes in pressure that could cause a backflow are effectively mitigated. When correctly installed, the anti-back-siphon device maintains a physical barrier that keeps fertilizers and other contaminants from infiltrating the potable water supply, thereby protecting groundwater resources.

The other options, while related to water management or equipment, do not specifically address the issue of preventing backflow. A water filtration system primarily focuses on removing impurities from water but does not prevent reverse flow. A drainage system manages excess water but does not prevent contamination of wells. A pumping station is designed to move water but does not inherently include mechanisms to protect wells from contamination during operations.