The aim of the diploma thesis was to propose optimal conditions of dosing of coagulants based on model experiments. The thesis consists of the four chapters; is divided into the two parts. The first part is the theoretical one. This part describes the treatment of the surface water for drinking, then the coagulation process and, for comparison, are reported examples of surface water treatment in the world. The second part deals with the characterization of the Nová Bystrica Water Treatment Plant and describes in detail the methodology of the work. In the result section the additions of the individual coagulants and their influence on water quality are evaluated. The effective MO PAC 18 coagulant was selected from the perspective of an optimal economic advantageous MO PAC 18 coagulant.