The present invention relates to a water treatment composition comprising blended phosphates which exhibit a synergistic effect for corrosion and scale control and as a sequestering chemical treatment of potable water and more particularly to chemistry which lowers the phosphate concentration necessary to achieve effective corrosion prevention. The composition controls corrosion and cleans the water distribution line by removing scale, tuberculation, and biofilm. Sequestration of the heavy metals and soft metals such as iron, manganese, calcium, and magnesium provides complete solubility of the material to be removed from the metal surface. The inclusion of citric acid with the blended phosphate formula improves drinking water quality in 2 ways: 1) a reducing agent reverses the oxidation of metals which would convert metal to metal salts (copper/lead, etc.) and 2) by chelation, it encapsulates transition metal cations, especially Manganese and Iron, found while source water passes through the treatment process and the drinking water distribution piping network.