Operators of several drinking water systems that are vulnerable to contamination by synthetic and volatile organic chemicals have shown interest in modifying existing treatment plants to include granular activated carbon (GAC) adsorption. An important consideration in the evaluation of GAC treatment alternatives is the examination of cost factors. This article presents preliminary cost estimates for various applications over a range of system sizes and carbon bed lives. Costs related to postfilter adsorbers using steel pressure and concrete gravity contactors are examined, as well as costs associated with fluid-bed, infrared, and multihearth reactivation technologies. Includes 8 references, figures, tables.