AWWA JAW56655

A study at a Paris, France, treatment site investigated the identity and origin of a musty taste in drinking water. This case was not attributable to algal metabolites such as geosmin or 2-methylisoborneol. When standard analytical approaches could not pinpoint the suspect compound, the authors turned to a new and more sensitive analytical approach: large-volume gas chromatography-mass spectrometry. The musty taste was traced to the presence of 2,4,6-tribromoanisole, a compound with an extremely low odor threshold concentration of 30 pg/L. In this case, a storage tank with a cement-based coating leached tribromophenol, which converted to tribromoanisole in the tank and imparted a musty odor to the water. This study highlights two important concerns for distribution systems: many cases of earthy-musty off-flavors will remain unsolved unless more sensitive measures, capable of detection limits of subnanograms per litre, are used; and, utilities should be aware that inappropriate distribution system coatings can lead to serious taste and odor problems. In Paris, French health authorities had approved the coating material for drinking water contact, based on leaching tests carried out by the city's control laboratory. More extensive tests are required to determine precursors of biologically formed products that may later affect water quality. Includes 36 references, tables, figures.