Which type of pesticide has the highest probability of moving to groundwater?

The type of pesticide that has the highest probability of moving to groundwater is one that is soluble and persistent. Solubility indicates that the pesticide can easily dissolve in water, which increases its likelihood of being transported through water movement in soil. Persistence means that the pesticide remains in the environment for an extended period, leading to a greater chance of it being leached through the soil and into groundwater without decomposing or breaking down quickly.

When solubility and persistence work together, even small quantities of these pesticides can be mobilized by water, particularly during events such as heavy rainfall or irrigation. This creates a considerable risk for groundwater contamination. The presence of soluble, persistent pesticides in soil can lead to extensive movement through the soil layers, where they can reach aquifers and contaminate drinking water supplies.