The present study focused on characterization of leachate generated from Thirupperunthurai dumpsite and ascertaining the magnitude of dumpsite pollution on groundwater quality. The leachate and well water samples from the vicinity of dumpsite were collected and analysed for some physicochemical parameters such as pH, Dissolved Oxygen (DO), Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Nitrate and Phosphate. The results showed that the leachate at dumpsite is in methanogenic phase with high concentration of pollutants. The pH of well water samples ranged from 6.5-8.2. The DO, EC, TDS, TH, Nitrate and Phosphate ranged from 2.86 mg/l - 4.93 mg/l, 240 μS/cm - 2686 μS/cm, 120 mg/l - 1340 mg/l, 66 mg/l - 207 mg/l, 43 mg/l - 172 mg/l and 0.31 mg/l - 1.47 mg/l, respectively. Groundwater flow direction greatly influences on level of pollution in well water near the dumpsite. Water quality parameters except pH and TH exceeded the maximum allowable limits for drinking purpose at some locations. Positive correlation was found between parameters except DO. Further, tested parameters except DO showed negative correlation with distance from dumpsite. Overall, groundwater in this study area is polluted by generated leachate, especially in the vicinity of the dumpsite. Therefore, existing dumpsite should be upgraded to a well-engineered standard landfill to prevent future contamination of groundwater in this area.