Which of the following is an example of a non-point source?

• A. A single pipe discharge
• B. A municipal wastewater treatment plant discharge
• C. A factory effluent pipe
• D. A landfill

Answer: (D)

Non-point source pollution comes from many diffuse sources rather than a single identifiable outlet. It typically results from runoff, infiltration, and leaching processes that pick up pollutants across a landscape and move them to a water body. A landfill fits this idea because contaminants can enter the environment through multiple pathways: leachate can migrate through soils and groundwater, and rainfall draining off the landfill can carry pollutants into nearby streams. There isn’t one discrete discharge point to identify. The other options describe definite outlets: a single pipe discharge, a municipal wastewater treatment plant outfall, and a factory effluent pipe are all identifiable point sources.