The paper deals with the topical, however controversial issue of the impact on the hydrodynamic resistance of polymer solutions of certain reagents that have proven to be already used in water supply for water disinfection, have anticorrosive activity and are safe for humans and the environment. The practical significance of this theoretical problem is that its solution can positively influence the achievement of energy saving at water supply companies without significant engineering and technical operating costs, as well as the management of environmental risks in extreme situations requiring significant water consumption (fires, human-caused accidents, etc.). The studies were carried out using tap water (with a total hardness of 3.70 mg-eq/dm3), polyhexamethylene guanidine hydrochloride (PHMG-HC) aqueous solutions. The pipeline model was fire hoses to a manual fire-hose nozzle RKS-50. In the modelling studies, a pumping unit with adjustable water flow rate and supply pressure was used, i.e., measurement of the main flow parameters in the feed pipeline depending on the parameters of the resulting jets. The results of statistical data processing are presented in figures and in the form of a polynomial. It has been experimentally established that PHMG-HC aqueous solutions in the concentration range of 0.001% to 0.3% exhibit hydrodynamic activity, and their flow rates depend on the polymer concentration in the solution and the pressure in the hose line. Thus, when adding PHMG-HC aqueous solution, the maximum increase in fluid flow occurs at a pressure of 2 bar and reaches ~10% to 11% (taking into account the error of laboratory set-ups and metrological equipment). The obtained research results allow us to assume that the hose line and fire-hose nozzle under these conditions operated in the mode of reducing hydrodynamic resistance by almost 10%, which, according to the authors, is due to a decrease in the friction of the fluid surface in the fluid pumping system. In order to specify the conditions under which effective practical use of PHMG-HC aqueous solutions is possible, as evidenced by preliminary assessments of technical and economic efficiency, it is planned to conduct field tests.