This study is based on comparative study of different water quality parameters such as pH, turbidity, electrical conductivity (EC), chloride, total solids (TS), total dissolved solids (TDS), hardness, color, dissolved oxygen (DO), total coliform (TC), fecal coliform (FC) and total chlorine for both raw water and reverse osmosis treated water from four different locations. Most of the water quality parameters tested for raw water was above the permissible limit according to World Health Organization (WHO) with the exception of turbidity and total chlorine. All the contaminants had a removal efficiency more than 90% except hardness (57.71%) and turbidity (22.50%) for treated water. The water quality index (WQI) shows that raw water from all four locations belongs to the poor water category and treated water belongs to the excellent water category. The highest monthly cost for the electricity being monitored is 38.1 Tk. ($0.45). The maximum water production was noticed for the month of october at 1021 liters and the per cubic meter water production cost for RO water treatment system was at 27 Tk. ($0.32).