Modern technological schemes in water supply for clarifying surface water include using reagents as coagulants, flocculants, etc. To mix them with the source water on plants usually use different types of mixing devices. Tubular mixer is one of such devices. Our research work involves the study of a tubular mixer with improved design, which can mix several reagents with source water. The paper presents theoretical and experimental studies of the tubular mixer with improved design for mixing several reagents with natural water. It is theoretically and experimentally substantiated the feasibility of using this tubular mixer for mixing several reagents with natural water over a short mixing time. The improved design of tubular mixer can mix several reagents with natural water in a short mixing time, intensify the mixing process and improve quality of water after treatment.