The main task of any country associated with sanitary and epidemiological welfare of population is to obtain drinking water of good quality. In the majority of regions of the Russian Federation, quality of water taken from water sources and water supply systems is still unsatisfactory. As far as the extent of human impact on the environment goes, the Samara region is an ecologically unfavorable part of the Volga region. With the accession of the Republic of Crimea to the Russian Federation, the problem of water supply here has been intensified and the question of whether the drinking water corresponds to Sanitary Rules and Regulations 2.1.3685–21 and Sanitary Rules and Regulations 2.1.3684–21 arose. The purpose of the study is to analyze quality of drinking water supply in the regions of the Russian Federation. Drinking water samples taken from the centralized domestic water supply system in the Samara urban district and Republic of Crimea were analyzed using 20 sanitary and chemical parameters. Quality of drinking water doesn’t correspond to the requirements for oil products in all samples; the average value of this parameter exceeded the maximum permissible limit by 0.18 mg/dm³ in the Samara urban district and by 0.04 mg/dm³ in the Republic of Crimea, all the other parameters were within normal limits. However, during the comparative analysis quality of drinking water in the Republic of Crimea was insignificantly better than in the Samara urban district. Quality of drinking water is determined with the source of drinking water supply (surface and underground). Thus, to make the prepared drinking water normal, a respective water treating is necessary. Bad condition of water supply pipes can also produce a negative impact on quality of water obtained by a consumer.