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Historical data suggests that the leading cause of consumer dissatisfaction with tap water qualityinvolves chlorinous taste and odors. In this work, chlorinous flavor sensitivity testing wasconducted in France and in the U.S. with untrained panels to confirm the taste thresholds of freechlorine and chloramine. This was compared to the results with a French Flavor Profile Analysis(FPA) panel.The answers of untrained panelists were found to be more heterogeneous than those of trainedpanelists. In other words, the free chlorine concentration had to be significantly increased to bedetected by the majority of the untrained panelists. The heterogeneity in human sensitivity ofboth untrained panels were similar, but the U.S. consumer panel was 5 to 10 times less sensitivethan the French consumer panel to free chlorine and monochloramine, respectively (0.2 +/- 0.05vs. 0.9 +/- 0.25 mg/L for free chlorine and 0.18 +/- 0.05 vs. 1.8 +/- 0.4 mg/L for monochloramine).This result may be linked to chlorination residuals practice in the different countries (0.1 - 0.2mg/L in France vs. 1.0 - 3.0 mg/L in the U.S.). In the background Total Dissolved Solids (TDS)experiments, no significant influence of water characteristics on panelist sensitivity to freechlorine or chloramine was noticed. In addition, there was no significant influence of changes intemperature (in a range between 15 - 25C) on free chlorine taste perception by untrainedpanelists.It is difficult to define a common target in terms of free chlorine residual based on consumerperception and almost impossible in terms of consumer tolerance.Geographical/cultural differences may be partly explained by the difference in local freechlorination practices.For practical reasons, it is easier for water utilities to rely on a laboratory panel rather than aconsumer panel for the monitoring of drinking water organoleptic quality. When interpretingpanelist data, utilities should keep in mind that a trained panel may significantly overestimate thechlorine perception of average consumers, whatever the taste testing method. Includes 7 references, tables, figures.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 8File Size: 1 file , 330 KB