The concentrations of physico-chemical parameters and heavy metals in water samples collected from Bayelsa State water Board Tank in Okaka, Yenagoa, Nigeria were investigated, and the water quality was assessed. Weekly Changes in Physicochemical parameters such as pH, Salinity, Conductivity, turbidity, Total dissolved solids, Total suspended solids, NO3,Cl- SO4 2-, HCO3 - , Total alkalinity, Total hardness, Dissolved oxygen, calcium, magnesium, potassium, sodium, manganese, iron, cobalt, copper, lead, zinc, cadmium were analyzed for a periods of four weeks. Comparison with WHO reference standards, studies from other environments and Pearson correlation matrix was attempted. The results of this study were found to be within permissible levels recommended by WHO, 2005.