2-METHYLISOBORNEOL (MIB), GEOSMIN AND2,4,6-TRICHLOROANISOLE (TCA)

Taste and odour compounds can arise from a number of biological and chemical sources. Three common contributors to the unpleasant taste and odour of water are 2-methylisoborneol (MIB), geomsin and 2,4,6-trichloroanisole (TCA).

MIB and geosmin: are metabolites produced by certain groups of benthic and pelagic aquatic microorganisms associated with lakes, reservoirs and running waters. Terrestrial ecosystems, industrial waste treatment plants and drinking water treatment plants may also be biological sources, but are often overlooked. MIB has a distinct musty/earthy odour and geosmin an earthy/grassy odour. A level of 10ng/L or more of MIB or geosmin (or combined total) is considered to be above the human taste threshold.

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2,4,6-Trichloroanisole (TCA): the third of the compounds analysed is a product of microbial transformation of chlorophenols formed when active chlorine species react with dissolved organic matter. The compound imparts an unpleasant musty/mouldy taste and odour to source and drinking water and has a taste/odour threshold of