BACKGROUND Contamination of water, food, and environment with antibiotic-resistant bacteria poses a serious public health issue. OBJECTIVE The objective was to study the bacterial pollution of the natural sources of water in east Sikkim and to determine the antimicrobial profile of the bacterial isolates. METHODS A total of 225 samples, 75 each during winter, summer, and monsoon season were collected from the same source in every season for bacteriological analysis by membrane filtration method. Antibiotic susceptibility test was performed using standard disc diffusion method. RESULTS A total of 19 bacterial species of the genera Escherichia, Klebsiella, Proteus, Salmonella, Shigella, Enterobacter, Citrobacter, Morganella, Pseudomonas, Acinetobacter, Flavobacterium, and Serratia were isolated and their antimicrobial sensitivity tested. Generally, most bacterial isolates except Salmonella and Shigella species were found resistant to commonly used antibiotics such as ampicillin (57.5%), trimethoprim/sulfamethoxaole (39.1%), amoxicillin/clavulanic acid (37.4%), cefixime (34.5%), tetracycline (29.1%), ceftazidime (26.3%), ofloxacin (25.9%), amikacin (8.7%), and gentamicin (2.7%) but sensitive to imipenem and piperacillin/tazobactam. CONCLUSIONS Natural sources of water in east Sikkim are grossly contaminated with bacteria including enteropathogens. The consumption of untreated water from these sources might pose health risk to consumers.