Which characteristic typically indicates a pesticide's potential to leach into groundwater?

The characteristic that indicates a pesticide's potential to leach into groundwater is its solubility in water. Pesticides that are highly soluble can easily dissolve in water and, therefore, have a higher likelihood of moving with water through the soil profile. When rain or irrigation occurs, these soluble pesticides can be transported downward and potentially reach groundwater sources.

In contrast, while persistence in soil can influence how long a pesticide remains active in the environment, it does not directly determine its capacity to leach. Formulation type may affect the pesticide's application, efficacy, and environmental impact, but it is not a direct indicator of leaching potential. Application method might influence the immediate area of concentration or runoff, but solubility is the key factor that relates to a pesticide's mobility in water and, consequently, its likelihood of contaminating groundwater sources.