Abstract <p>The Triund trek near McLeodganj, India, attracts a significant influx of tourists annually. However, the lack of sanitation facilities has led to rampant open defecation at and around the campsite, resulting in fecal contamination of water sources. In the present study, we have used drainage basin classification to identify water sources in the Bhagsunag region that could be a potential sink for the fecal contamination passing through surface runoff from Triund. The analysis shows that Bhagsunag waterfall, the primary water source for the region, is a part of the drainage basin receiving this contaminated runoff, further exacerbating the risk. Water samples collected from the Triund campsite and Bhagsunag area revealed exceptionally high total dissolved solute (TDS) values and elevated conductivity and coliform levels. The snowline water, initially fresh, accumulates fecal matter as it flows downstream, primarily due to open defecation at the campsite. This results in pathogen load in lower-altitude water sources. Water quality index (WQI) values for most samples were &gt;100, making them unfit for consumption or domestic use. To effectively address the contamination issue, implementing Eco-San toilets at the Triund campsite is recommended due to their water-efficient, closed-system design, making them a superior alternative to other options. The findings underscore the urgent need for sanitation infrastructure improvements and policies to mitigate open defecation, which poses a direct threat to both ecological integrity and public health in the Bhagsunag region. Immediate action is critical to prevent further environmental degradation and health hazards in this high-altitude ecosystem.</p>