The earthy or musty taste or odor in drinking water in the Upcountry district is caused by an increase in the existence of Geosmin and MIB (2-methyl isoborneol). These compounds are naturally occurring and are produced by the decaying of leaves and other organic material.
Geosmin produces an odor similar to overturned rich soils and is present in foods such as beets, spinach, and mushrooms. MIB are naturally occurring compounds found in surface waters as organic molecules produced by algae. The substances are detectable by the human nose even at very low concentrations, and some individuals are extremely sensitive to Geosmin. Neither compounds are harmful to people.