The paper presents the results from studies upon the influence of chemical structure of filtration masses used for the treatment of groundwater on the values of selected physicochemical parameters of water. The pH value of treated water and the redox potential are important in process the oxidation of iron and manganese compounds. These values may change as a result of water contact with filter materials. The value of zeta potential of filtration masses characterizing the surface charge of particles and their affinity to counter-ions, is also important. The study tested masses of different chemical structure, i.e. manganese ores and de-acidifying masses. Experiments were carried out at two different pH values of the model water. The results showed that the filtration masses affected the water quality and water treatment processes, and the type and magnitude of changes in physicochemical parameters are closely related to, among others, the chemical structure of the filter bed.