The Status Quo of Causal Substance Exploration for Fishy Odor in Raw Water for Taps

Algal bloom in a closed water basin is sometimes problematic, especially in terms of the off-flavor in tap water because of an increased amount of odorous metabolites produced by them. Unfortunately, the current water purification process does not always function properly to remove odorants in tap water. Fishy odor is one of the most frequently detected off-flavor in tap water across the world and a number of papers have studied its occurrence mechanism; however, the determination of its causal substance remains rather formidable. The objective of this review paper is therefore to pave a way for unequivocal identification of a causal substance of the fishy odor. We propose that focusing on already reported odorants is not enough to achieve this; an unknown odorant possibly contributes to the occurrence of the fishy odor. An extensive exploration using a novel technique, such as a combination of high-resolution mass spectrometry and multivariate analysis, can be a promising methodology to discover proper odorant.