|This study was performed to estimate the corrosion characteristics of corrosion inhibitor using the simulated water distribution system. The alkalinity and pH showed a slight increase for all pipe materials with the corrosion inhibitor of 2.2mg PO₄/L. The turbidity was lower with 2.2mg PO₄/L of the corrosion inhibitor than that without. At the constant concentration of 2.2mg PO₄/L of the corrosion inhibitor, the elution concentration of heavy metals was analyzed for a carbon steel pipe, a galvanized steel pipe, and a copper pipe. For the carbon steel pipe with the corrosion inhibitor, the eluted metal concentration after 30 days was reduced, but not significantly. With galvanized steel pipe, the eluted zinc concentration was decreased by 38%, and iron by 52% at 2.2mg PO₄/L of corrosion inhibitor. With the copper pipe the eluted copper concentration was decreased by 60 % at 2.2mg PO₄/L of corrosion inhibitor. After 60 days, the weigh loss analysis indicated that the corrosion rate at 2.2mg PO₄/L of corrosion inhibitor was reduced by 38, 50 and 72% for the carbon steel pipe, galvanized steel pipe, and copper pipe, respectively.