The purpose of this study was to determine the conditions under which removal of the taste- and odor-causing compounds geosmin and 2methylisoborneol (MIB) by powdered activated carbon (PAC) was most efficient. It was observed that a PAC dosage as low as 5 mg/L could reduce commonly occurring concentrations of these organics (up to 20 mg/L) to acceptable levels. Chlorine and monochloramine residuals appeared to have an adverse effect on the adsorption of geosmin and MIB by PAC, as did the presence of background humic acid. Filtration rate and contact time did not significantly affect removal efficiency. Includes 15 references, figures.