Introduction. The modern highly sensitive methods of controlling substances that affect humans in real environmental conditions are necessary to adequately assess the quality and chemical safety of drinking water, including pesticides used in agriculture for the destruction of weeds and pests. The aim of the work was to improve the sensitivity of existing techniques for the determination of triazine pesticides in their joint presence to control drinking and bottled water. Material and methods. The studies were performed using a chromatography mass-spectrometric system including a liquid chromatography with tandem mass-spectrometric triple quadrupole detector. Results. The influence of various factors on the extraction of triazine pesticides from water has been studied, the chromatographic and detection conditions have been optimized. Linearity in the range of 0.1 - 10 μg / dm3 is proved. The limits of detection and quantitative determination of triazine pesticides in drinking water are established in accordance with hygienic standards. Discussion. The procedure allows separate determination of triazine pesticides when they are co-located in concentrations at and below the corresponding MPC values in drinking and bottled water. The method allows reliably determining the target compounds without the use of hard-to-reach deuterated reference materials. To improve the reliability of the method, as an internal standard it is recommended to use one of the compounds studied, which is not a widely used pesticide, for example, propazine, with mandatory control of the initial matrix for its content. Conclusion. A highly sensitive method for the separate determination of a group of triazine pesticides (simazine, atrazine, propazine, prometrin, metribuzin, metamitron) was developed with their joint presence in drinking water with sensitivity at or below the corresponding hygienic standards. © 2020 Izdatel'stvo Meditsina. All rights reserved.