To improve water quality, there should be a mechanism of keeping safe water source from chemical contaminants in an effective and protective way through the application of regular checkup and with interventions by taking exact measure periodically before it is supplied for usage. The intention of this research is aimed at determining the level of common cations, anions, heavy metals and physical parameters in drinking water supply system in, Konso and its surrounding area, Southwestern Ethiopia. Water samples were collected from 23 different locations in the area where there is a hand pump or motorized supply system that is used for drinking purpose. The collected samples were analyzed for physicochemical parameters including total alkalinity, temperature, pH, electrical conductivity, total dissolved solids, turbidity, alkalinity, total hardness and total suspended solid. Common cations (Li + , K + , Na + , Ca 2+ and Mg 2+ ), common anions (NO 3 -, SO 4 2-, PO 4 2-, F -and Cl − ) and heavy metals (Pd, Ni, Mn, Pb, Co, Zn, and Cu) were analyzed. Accordingly, the results obtained show that most of the physical and some common ions and heavy metals were within the accepted range of the guideline recommended by WHO. However, some parameters are at alarming state as compared to the WHO standards for drinking purposes, thereby suggesting the need for treatment and precautionary measures for use of the particular ground water.