Groundwater sources play an important role in meeting the day today needs of the present generation. Frequent monitoring of the ground water source plays an important part. The aim of this study is to analyze the quality of the ground water in and around the solid waste dumpsite near Sathyamangalam town in Erode district and to identify the variation in concentration with respect to time. Groundwater samples were collected from twenty-one locations and analyzed for pH, Electrical conductivity, Total Alkalinity, Total Hardness, Total Dissolved solids, Calcium, Magnesium, Chlorides, Sodium, Potassium, Nitrates and Sulphates. The collected groundwater samples were analysed using “Weighted Arithmetic Index” and the water quality was indicated using WQI - a number used to identify the water quality easily by the general public. From the results obtained, it is inferred that Water Quality Index changes with respect to pre-monsoon and post monsoon seasons and different time periods for the same location. The changes in water quality are not fully influenced by the open dump site and it may be due to weathering of rocks, use of fertilizers in agricultural lands. Majority of the samples are of poor quality with respect to drinking water quality index. Gibb’s plot, Wilcox diagram and United States Salinity Laboratory diagram are used to assess the suitability of groundwater samples for irrigation purpose. Most of the samples are good for agricultural use. Hence frequent and continuous monitoring of the groundwater quality is necessary to identify its suitability for drinking and agricultural purpose.