A pilot plant study was performed to investigate both the effect of silica on the corrosion process in the water system, and the effect of increased oxygen concentration resulting from ozonation on copper corrosion in the water system. The piping system used in the pilot plant resembled a household piping system, and consisted of four loops of copper pipes. Silica was added to the finished water before entering the loops at three different concentrations and corrosion was monitored by measuring copper concentration in first-draw weekly samples taken from the pilot system. Silica addition was monitored on a daily basis. Alkalinity, pH, dissolved oxygen, temperature, and conductivity were also measured, and the corrosivity of each water was calculated; Statistical and thermodynamic chemical analysis were performed to evaluate the results in chapter, and the most effective dosage of silica was determined. An average of 11.3 mg/l applied silica concentration was found the most effective dosage in retarding the corrosion rate. Increased in dissolved oxygen concentration had insignificant effect on dissolved copper concentration; A multiple linear relationship was found to predict copper concentration in loop 1, where no silica was added, as a function of alkalinity and temperature. It was also found that the formation of Cu(OH){dollar}\sb2,{dollar} Cu(CO{dollar}\sb3),{dollar} CuHCO{dollar}\sb3\sp{+1},{dollar} and Cu(CO{dollar}\sb3)\sb2\sp{-2}{dollar} were thermodynamically favored under the experiment conditions in loop 1
