Groundwater samples collected at different locations in and around Nagapattinam district were analyzed for their physicochemical characteristics. The groundwater samples were collected from 52 dug wells and deep boreholes during the monsoon and summer sub seasons in the month of June and December (2011). The present investigation is focused on the determination of physicochemical parameters such as pH, EC, TDS, Ca, Mg, Na, K, HCO3, SO4 and Cl. Groundwater suitability for drinking, domestic irrigation purposes was examined by using WHO standards. Correlation, factor and cluster analyses were applied to classify the groundwater samples and to categorize the geochemical processes controlling groundwater geochemistry. Factor analysis indicates that seawater intrusion and agriculture runoff are the dominant factors controlling hydrogeochemistry of groundwater in the study area. Cluster analysis was helpful for the classification on the basis of the contamination characteristics of groundwater quality. This present study also elucidates that the combined statistical analysis to improve the understanding of groundwater status and assessment of groundwater quality.