Background & Objectives: Pollution of water resources to organic matters and their associated problems including taste, odor, and formation of disinfectant by-products require evaluating removal methods for these materials from drinking water. This study aimed to evaluate performance of organic matter removal from water using deaerating system. Methods: A PVC pilot deaerator tower (diameter=15, height=140 cm) was designed, constructed, and used for this study. The system was loaded in flow rates of 0.6, 0.8, 1, 1.2, and 1.5 l/min. Absorption of samples were measured at wavelength of 253.7 nm and COD was determined for all samples. Results: COD levels and absorption rates of samples decreased with time for flow rates of .6, 0.8, 1, and 1.2 l/min. However, absorption rates and CODs increased with increasing flow rate (except for flow rate of 1.5 l/min). Conclusion: Deaeration tower system has capability to remove organic matters from water and the highest efficiency was observed at low flow rates. In addition, significant relationships (R2>0.95) was observed between COD and absorption rates (except for flow rate of 1.5 l/min), and that COD may be measured through determination of absorption rate at UV wave length.