Changes in the indicators of chemical safety of drinking water in Ufa during its transportation to consumers

Introduction. To conduct a total assessment of carcinogenic, non-carcinogenic, and organoleptic risks to public health and cover both normalized and non-normalized pollutants of potable water, based on the results of long-term monitoring studies, it is possible using an integral indicator of chemical harmlessness of water. Material and methods. Authors studied potable water of water intakes of surface and infiltration types from potable water reservoirs and remote zones of Ufa water distribution networks. Impurities were determined by chromatography, inductively coupled plasma mass spectrometry, photometric, nephelometric, and titrimetric methods.  Results. The main effect on the amount of carcinogenic risk in potable water of the surface water intake are chloroform, bromodichlethane, dichloroacetic acid, in the infiltration water intake - in addition to these compounds zinc, lead and chromium are in addition influenced. Organic compounds (phthalates, benz(a)pyrene, volatile aromatic compounds, etc.) have no effect on this type of risk due to the presence in water in low background concentrations. The identified number of individual carcinogenic risks for bromodichloroacetic acid and dichloroacetic acid according to the WHO classification corresponds to the second range. As the surface type water intake is removed from the potable water reservoir, the total carcinogenic risk of water decreases by 13-30%, and the infiltration type increases by 41-84%. Values of noncancerogenic and organoleptic risks are constant for potable water of different water intakes and correspond to recommended limit values. The excess of the maximum permissible concentrations (SanPin 1.2.3685-21) of individual substances in the potable water of the city has not been detected for the whole period of observation. In terms of the integral indicator of chemical harmlessness, the most favorable is the po-table water of the infiltration water intake, in the technology of which is mainly used the UV for decontamination of water. Conclusion. Using a risk assessment methodology complements the traditional approach to assessing water quality under modern hygiene standards. It becomes possible to evaluate the effect of pollutants of various classes on water quality when they are present together.