Demonstration of new sensory methods for drinking water taste-and-odor control

In order to demonstrate the practicality of two newly developed taste-and-odor methods, raw and filtered water samples from the Songchon water treatment plant, and tap water samples from houses were analyzed from July to October 2000 using three sensory methods (TON, 2-out-of-5 odor test and attribute difference test for the presence or absence of geosmin) and one instrumental method (closed-loop stripping analysis, CLSA, followed by gas chromatography, GC). Comparison of TON values with CLSA indicated a discernible relationship only when the odorant level was relatively high. The two newly developed methods, however, were more sensitive than TON when the odor intensity of samples was low. The attribute rating test for geosmin is more sensitive than the 2-out-of-5 odor test when the TON value is less than 10. These new methods seem better than current methods for identifying the occurrence of odor compounds in raw and filtered waters. They also have practical use in tracking the efficiency of treatment methods, such as adsorption and oxidation, used for controlling taste-and-odor episodes.