Odors and Tastes In Water

Here are some typical complaints about tastes and odors in water:

• sewer smell;
• chlorine smell;
• chlorine smell and taste;
• rotten egg smell;
• petroleum smell or taste;
• metallic smell or taste; and
• earthy or fishy smells and tastes.

Here is a good tech brief about odors and tastes in water which describes the sources and solutions to the above problems.

The distinctive odor of feces is due to bacterial action. Gut flora produce compounds such as indole , skatole , and thiols ( sulfur -containing compounds), as well as the inorganic gas hydrogen sulfide . These are the same compounds that are responsible for the odor of flatulence . Consumption of foods with spices may result in the spices being undigested and adding to the odor of feces. The perceived bad odor of feces has been hypothesized to be a deterrent for humans, as consumption or touching it may result in sickness or infection. Of course, human perception of the odor is a subjective matter; an animal that eats feces may be attracted to its odor.

Geosmin , which literally translates to "earth smell", is an organic compound with a distinct earthy flavor and aroma, and is responsible for the earthy taste of beets and a contributor to the strong scent ( petrichor ) that occurs in the air when rain falls after a dry spell of weather or when soil is disturbed. 2-methylisoborneol (MIB) is also controbuting to this smell.

Geosmin is produced by several classes of microbes , including cyanobacteria (blue-green algae) and actinobacteria (especially Streptomyces ) , and released when these microbes die. Communities whose water supplies depend on surface water can periodically experience episodes of unpleasant-tasting water when a sharp drop in the population of these bacteria releases geosmin into the local water supply. Under acidic conditions, geosmin decomposes into odorless substances.

Putrescine (sometimes spelled putrescin ) is a foul-smelling organic chemical compound N H 2 ( C H 2 ) 4 NH 2 (1,4-diaminobutane or butanediamine) that is related to cadaverine ; both are produced by the breakdown of amino acids in living and dead organisms and both are toxic in large doses. The two compounds are largely responsible for the foul odor of putrefying flesh, but also contribute to the odor of such processes as bad breath and bacterial vaginosis . They are also found in semen and some microalgae, together with related molecules like spermine and spermidine .

Rami E. Kremesti M.Sc.