AWWA JAW18761

Two episodes of unacceptable tastes and odors, which corresponded with levels of geosmin in the water that were much higher than the background level of 20 ng/L or less, occurred in Philadelphia during 1985. The source of one episode was found to be a localized bed of algae in the Schuylkill River. An existing taste and odor control program, which utilizes instrumental and sensory analyses, was largely responsible for the effective management of the episodes. Hydraulic strategies were used to reduce the treatment plant's intake of geosmin, and powdered activated carbon in the treatment train further reduced the geosmin level. Dilution of this treated water with other finished waters in the distribution system also diminished the impact of geosmin on the taste and odor of Philadelphia's water. Includes 20 references, tables, figures.