Microfiltration (MF) and powdered activated carbon (PAC) adsorption were combined to treat waters contaminated with organic compounds. The PAC mitigates the effects of membrane fouling and concentration polarization by removing dissolved organic matter such as humic substances. The investigation used trichloroethylene (TCE) as a model contaminant and deionized distilled water and California Aqueduct water as background solutions. Removals of >99.8 percent of TCE and >60 percent of dissolved organic matter were achieved. Steady-state permeate fluxes of 10-20 m3/m2/d (250-500 gpd/sq ft) were easily maintained. The total cost of treatment with MF-PAC was estimated to be $1.27 per 1,000 gal of treated water. A three-layer membrane transport model provided a qualitative appreciation of the MF-PAC. Includes 21 references, figures.