Aquifers in general are prone to contamination due to various factors including anthropogenic activities; monitoring the water quality by cost-effective techniques is of great significance and use. To study the water quality of around 100 open wells in Trichy district, Tamilnadu, India, the analytical tool ‘geographical information system’ (GIS) was applied and the outcome analyzed. The district, based on the soil type, is categorized into three regions viz: unconsolidated (Recent), semi consolidated (Cretaceous to Miocene) and consolidated (Archaean), and this technique was applied for the water samples collected in those regions. A spatial variation in well waters in the district was studied using GIS based on 15 physico-chemical parameters. For the three regions in the district, the water quality information maps of the entire district have been prepared using a spatial interpolation technique for these parameters. Statistical analyses carried out for the parameters and the character of water related to source of supply and changes in water qualities are discussed. Also the Piper tri-linear diagram is plotted, which shows the essential chemical character of the groundwater in these open wells. The condition of the groundwater has been categorized as good, moderate and poor in the respective maps for the pre and post-monsoon seasons, with the perspective of location of the site as well as in the nature of aquifer formation. Suggestion is given for the strategies for the development and preservation of the groundwater condition in this region.