The aim of the study was to use regenerated activated carbon to adsorb phenol from a river. Coconut shell activated carbon was derived from used tap water filter cartridges. The activated carbon was carbonised and then activated with KOH at 200°C, under a nitrogen atmosphere. The resulting adsorbent was characterised on the basis of nitrogen adsorption by Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) analysis and point of zero charge (pH PZC). The study of periodic adsorption included kinetic and equilibrium modelling, determined the effect of solution pH on efficiency and the possibility of regeneration and reuse of the adsorbent. The efficiency of phenol removal from model water was evaluated, followed by the possibility of their adsorption from a polluted river in Silesia Province. Phenol adsorption followed pseudo-second-order kinetics. The adsorbents showed high adsorption abilities, as determined by the Langmuir isotherm model. The model fits the experimental data well. The concentration of phenol in the river was in the range of 0.45–0.77 mg∙dm– ³, which means that its value was at least five times higher than the standard values. The use of regenerated activated carbon from waste filter cartridges removed phenol from the river by 78% using optimal test parameters.