An attempt has been made for the first time in this region to assess the groundwater quality and the suitability of groundwater for drinking and irrigation purposes systematic studies which are significant for assessment of water quality have been carried out to find out the area for sources of dissolved ions in groundwater of Periyapatna taluk, part of upper basin, which is one of the sub basins of Cauvery River, Karnataka. One hundred and twenty samples have been collected from different bore wells for two seasons (Pre-monsoon and Post-monsoon.) The physico chemical parameters such as hydrogen ion concentration (pH) and Total Dissolved Solids (TDS) were measured in addition to major cation and anion concentrations. A comprise of ground water quality is relation to drinking water standards was made. The pH values of ground water for pre monsoon season in this area range from 7.20 to a maximum of 9.50 and for Post monsoon season is 7.56 to 9.85.(from 6.50 to 8.50 for dug wells and bore wells receptively). The average pH value for the groundwater of the region is 7.20 which indicates slightly alkaline nature of water and are suitable drinking purpose. About 92% of groundwater samples fall in hard water category and there is a need for softening these waters if it is to be used for drinking and domestic purposes. All the samples are within the permissible limits as per standards proposed by WHO. In the most of the samples alkaline earths (Ca²⁺+Mg²⁺) exceeds alkalies 44.30% for pre monsoon and 56.40% for post monsoon season and  strong acids exceeds weak act 3.50% for pre monsoon and 1.80% for post monsoon season as per Pipers trilinear diagram based interpretation