The ground water quality is determined in five blocks (Udwantanagar, Tarari, Charpokhar, Piro and Sahar) that lays in southern parts of district Bhojpur district of Bihar, where from each block ten ground water samples are under studied for Physico- chemical status of ground water. In Physico-chemical analysis , various quality parameter are measured including pH, turbidity, electrical conductivity (EC), total dissolved solids (TDS),total hardness(TH),content of calcium (Ca2+),,magnesium (Mg2+),chloride(Cl-), sulphate (S04 2-), Iron (Fe), DO, BOD, COD, Total alkalinity (TA) and Nitrate (No3 2-) concentration present in ground water. Also all parameters were compared with ICMR standards of water quality; also in present research paper classification of water samples of five blocks was investigation on the basis of TDS and TH.