Water Quality Index for Assessing the Surface Water: A Case Study of Thamirabarani River, Kokirakulam

River water is the main source for domestic purpose and irrigation. It is often polluted due to discharge of untreated water from household and industries. The polluted water creates problems not only to human being but also to the animals and aquatic organisms. Many dreadful diseases are spread through contaminated water. Hence it becomes essential to analyze sources now and then to estimate the level of pollution. The Thamirabarani river water at Kokirakulam is analyzed for physico-chemical parameters and the Water Quality Index is calculated to predict the usability of water for drinking and domestic purposes. The 24 physico-chemical parameters and Escherchia coli count are analyzed. The Sodium Absorption Ratio (SAR), Kelly’s Ratio (KR), Percent Sodium (PS), Magnesium Ratio (MR), Chloro-alkaline indices and Water Quality Index (WQI) are computed. The results show that SAR of 26.39 indicating water quality as fair. Kelly’s Ratio, Percent Sodium and Magnesium Ratio exceeded the limits representing the unsuitability of water for irrigation or domestic use. The negative value of Chloro-alkaline indices expresses the possibility of exchange of sodium, potassium with calcium and magnesium. The Water Quality Index value is 957.86 shows that the water is unsuitable for drinking, irrigation, animals and aquatic organisms