The hydrochemical study of groundwater in Karur district of the Amaravathi River basin has been carried out to assess the major ion chemistry and groundwater quality for domestic and drinking purposes. Twenty-four groundwater samples were collected, processed, and analyzed for various physico-chemical parameters such as pH; electrical conductivity; total dissolved solids; total hardness; cations such as calcium, magnesium, sodium, and potassium; anions such as bicarbonate, chloride, sulfate, fluoride, nitrate, and phosphate in the laboratory using the standard methods given by the American Public Health Association (Standard methods for the examination of water and wastewater, 21st edn. American Public Health Association, Washington DC, 2005). For quality assessment, the results were compared with water quality standards prescribed by the Bureau of Indian standards (Indian standards specification for drinking water 15:10500. Bureau of Indian Standards, New Delhi, 2003) Concerning water for irrigation purposes, parameters such as percent sodium (% Na), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), chloro-alkaline indices (CAI I and CAI II), permeability index (PI), magnesium hazard (MH), Kelley's ratio (KR), USSL diagram, Gibbs' ratio (GR), and Wilcox diagram were calculated on the basis of chemical data to evaluate the current status of groundwater in the Amaravathi River basin. Parameters like MH (74 %), KR (75 %), RSC (95 %), and PI (69 %) in all three seasons indicate that the samples are suitable for irrigation and remaining are unsuitable. From USSL diagram, the result reveals that the samples fall in C3-S1 and C4-S1 indicate high to very high-salinity and lowsodium hazards. Wilcox diagram revealed out of 24 samples, sample no. 7, 8, and 11 in pre-monsoon, monsoon, and postmonsoon seasons fall under doubtful to unsuitable and 9 fall under unsuitable zone. The positive CAI values in 66 % samples in all three seasons indicate reverse ion exchange mechanism. The present study may be helpful for further studies concerning water quality issues in this area, where groundwater is a vital for drinking and other activities.
