An 11,500 cu m/day (3MGD) side stream of treated Passaic River water was routed to three pressure vessels in parallel, each containing a different commercial brand of granular activated carbon. For 13 weeks the virgin adsorbents were monitored for the following parameters: organic carbon, organic halogens, and thirty-six specific organic compounds. The adsorbents were regenerated on-site using an electric (infrared) tunnel furnace (45 kg/hr) and following regeneration, returned to service. This cycle was repeated three times. The efficiency of regeneration depended on the parameter used as the index of restoration. The iodine numbers, apparent densities, and effective sizes were virtually unchanged. The ash content increased while the capacity for removing free chlorine decreased upon regeneration. The ash content increase was probably the result of chloride and sulfide build-up. The capacity for removing total organic halogen was restored to about 50% of its original (virgin) capacity. The capacity for removing total organic carbon also decreased after the first regeneration, but then increased following the second and third regeneration. The pore volume and pore area were measured after the second regeneration, and both declined. Fluorometric and ultraviolet absorbance measurements did not prove to be useful surrogates for monitoring either regeneration or performance. The total cost of regeneration, excluding amortized furnace and appurtenances costs, was approximately $0.50/Kg (20 to 25 cents/lb) of activated carbon.