A combined scheme for wastewater treatment is proposed using a combined filter, which includes a reagent treatment section, a mixing chamber, a contact flocculation chamber and a sand-loaded filter. The main features of the operation of the mixing chamber located inside the filter housing are considered, which ensures the intensification of the coagulation process, due to the continuity of the coagulating and filtering process in a single housing without interrupting the process, due to which the flakes are not destroyed when moving from stage to stage. To confirm the efficiency of the mixing chamber, a number of laboratory experiments were carried out on model and river water. It has been confirmed that the use of the developed mixing chamber improves the filtration process by 15 to 30%. It was concluded that intensification of the filtration process would improve the efficiency of treatment facilities as a whole and ensure the quality of water for discharge into water bodies.