The invention pertains to a process for in-situ regeneration of activated carbon loaded with trihalomethane (THM). Based on the invention, this is achieved with alkaline hydrolysis of the THM with increased temperatures within the activated carbon in halogen-free, good water-soluble, or gaseous compounds. After completion of the chemical hydrolysis treatment, the activated carbon is cleared of reagents and reaction products by rinsing with water and diluted acids, and is then available for reloading in the untreated water flow. During the entire cleaning process, the activated carbon bed must not be moved.