Abstract
Abstract. The study focuses on evaluating the efficiency of local post-treatment and conditioning of tap water using "Zhivaya Voda" stationary water vending machines in Kokshetau. The aim of the work was to conduct a comparative analysis of the properties of initial tap water and permeate obtained after filtration and reverse osmosis. "TURAN" bottled table water was adopted as a benchmark for comparing physicochemical parameters. Sampling for laboratory analysis was carried out in three districts of the city. The membrane elimination capacity was calculated using the classic formula for baromembrane separation. It was established that the cascade filtration system provides 100% barrier efficiency against suspended solids, reducing turbidity to 0 NTU (Nephelometric Turbidity Units) and odor intensity by 1 point on the organoleptic scale. Spectrophotometric analysis demonstrated a high elimination rate of residual free chlorine (up to 96.0%), total iron (up to 78.6%), total chromium (up to 70.0%), copper (25.0–40.0%), manganese (up to 50.0%), and phosphate ions (up to 100%), alongside characteristically lower selectivity toward low-molecular-weight singly charged nitrate anions. The results indicate a significant improvement in the overall physicochemical profile of the water. A directional downward shift in water pH was recorded in the samples, driven by the membrane's retention of the hydrocarbonate buffer and the concomitant carbonic acid equilibrium shift. Meanwhile, the stability of total hardness values confirmed the efficiency of water conditioning in the integrated mineralization unit, which completely prevents deep demineralization. The data obtained demonstrate that water vending machines effectively bring tap water quality closer to the natural benchmark parameters, which allows recommending them as an accessible method for decentralized drinking water safety enhancement at the consumer level.