Which is an example of non point source contamination of groundwater?

• A. Back siphoning of pesticide spills at a wellhead.
• B. Leaching from pesticide mixing area.
• C. Pesticides that dissolve and leach through soil after it rains.
• D. Direct discharge from storage drum.

Answer: (C)

Nonpoint source contamination is pollution that enters groundwater from many diffuse sources across a broad area, rather than from a single identifiable discharge. When pesticides dissolve in water and move with infiltrating rain through the soil, they can travel downward from multiple fields and surfaces over a wide area into the groundwater. This leaching after rainfall represents a widespread, diffuse pathway rather than a single outlet, which is why it’s the example of nonpoint source contamination.

By contrast, back siphoning at a wellhead, direct discharge from a storage drum, or a spill from a pesticide mixing area all originate from specific, identifiable locations, making them point sources of contamination.