Which of the following is a potential source for surface water contamination?

• A. Industrial Solvent Discharge
• B. Noise Pollution
• C. Urban Environmental Runoff
• D. Septic Tank Leakage

Answer: (D)

Surface water contamination occurs when pollutants from the surrounding land reach streams, rivers, or lakes. Septic tank leakage provides a direct route for human waste to enter surface water, especially if a tank fails, is poorly sited, or is overwhelmed by heavy rainfall. The leaked wastewater can carry pathogens such as fecal bacteria and viruses and nutrients, degrading water quality and posing health risks for recreation, drinking water sources, and irrigation. While industrial solvent discharge and urban runoff can also contaminate surface water with chemicals or nonpoint pollutants, septic leakage uniquely represents a direct, biological pathway from human waste into surface waters. Noise pollution, by contrast, does not affect water quality.