Abstract-In Bangladesh, surface water (e.g., pond/river water) and rainwater are important sources of potable water, particularly in areas suffering from arsenic contamination of groundwater and high salinity. However, surface water often suffers from high microbial contamination and needs disinfection for potable use. Disinfection is a challenge for small water supply systems, as a family or small communities often do not have necessary facilities to disinfect water properly. Many commercially available household-level treatment systems are not effective in removing pathogens. This study presents an assessment of the effectiveness of UV disinfection for highly contaminated surface water. Disinfection experiments were carried out in a large (152 cm × 48 cm x 48 cm) container under different operational (e.g., UV lamp intensity, exposure time) and water quality (e.g., initial FC, turbidity) conditions. UV disinfection could significantly reduce microbial (FC) contamination from highly polluted surface water with initial FC concentration varying from 8,000 to 24,000 cfu/100 ml. The effectiveness of UV disinfection has been found to depend on a number of operational factors including intensity of lamp, exposure time, and distance from the lamp. Although FC concentration could not be reduced to zero (which is the national drinking water standard) under the experimental condition used in this study, the results suggest that this could be achieved with appropriate combination of lamp intensity, exposure time and tank dimension. Thus, UV disinfection could potentially be used for treatment of surface (pond/river) water in water scarce areas (e.g., arsenic-affected or salinity-prone areas).