What phenomenon occurs when liquid pesticides flow back into a water supply?

Backflow is the phenomenon where liquid pesticides or any other substances flow in the opposite direction within a plumbing system, potentially returning to a water supply. This can occur due to a change in pressure, such as when there is a drop in the water supply pressure that allows for the reversal of the flow. It is a critical issue in pesticide application because it can lead to contamination of drinking water or other surface waters.

Understanding backflow is essential for the safe use of pesticides, as it highlights the need for proper backflow prevention measures such as check valves or air gaps in irrigation and pesticide discharge systems. These protective measures ensure that harmful substances do not re-enter the potable water supply, safeguarding public health and the environment.