The April 2015 earthquake in Nepal resulted in the loss of 9000 lives, destroyed several infrastructures and displaced more than 2.3 million people. A study was conducted to analyze the perturbation in biological stability of the water sources compounded by poor sanitation practices in Kathmandu (severe earthquake damage) and Jhapa (no earthquake damage) using microbial source tracking and 16S rRNA sequencing. Samples from the same locations were taken before the earthquake in summer 2014, and then again in May to July, 2015 and in Dec. 2015, corresponding to one month and eight months after the 2015 earthquake. Microbial source tracking of human fecal contamination revealed the deteriorated sanitation practices in some specific sites in Kathmandu after the earthquake. The abundance of certain genera responsible for maintaining geobiochemical characteristics of water (Ammonia Oxidizing Archea and Bacteria, Nitrite Oxidizing Bacteria, Sulfate Reducing Bacteria), for example, Methylobacter, Nitrospira, Methylomonas, increased significantly right after the earthquake and decreased eight months later. This result indicated the disturbance in biostability of water right after the earthquake and also indicated the recovery of microbiomes with time. In addition, sudden spikes in some bacterial genera associated with opportunistic pathogens were observed after the earthquake, which associates with outbreaks observed after such event. This study highlighted the potential disruption of water microbiome after the earthquake and its restoration as a function of time and sanitation practices
