Effects of chlorine and chloramines on earthy and musty odors in drinking water.

Water treatment plants in the US may operate under the assumption that chlorine masks earthy and musty odors from geosmin and 2-methylisoborneol (MIB) in drinking water. To test this hypothesis, we evaluated the effects of chlorine and chloramines on geosmin and MIB by two sensory analysis approaches--a statistical Pairwise Comparison Test, and Flavor Profile Analysis (FPA). All Pairwise Ranking test statistics were significant (p<0.05); we conclude that panelists can differentiate minor differences in geosmin and MIB concentrations in a Pairwise Comparison Test even in the presence of chlorine. FPA appeared to be more challenging in discerning subtle differences in concentrations of geosmin or MIB than did the Pairwise Comparison Test, and the presence of chlorine (0.5-20 mg/L) and chloramines (3-24 mg/L) confused the panelists (i.e showed a larger error in the intensity of response reported by the panel), but did not necessarily mask geosmin or MIB.