Safe drinking water is one of the determining factors of human life quality. Modern climate and environmental problems increase the complexity of adequately solving the problem of providing the population with high-quality drinking water. The most common way to meet the need for safe water is central water supply. But even in countries with a high level of economic development, consumers are often dissatisfied with the quality of tap water, which leads to an increase in demand for bottled water and water purification devices used at home. According to Rospotrebnadzor, in Russia in 2023, about 15% of centralized water sources did not meet sanitary and epidemiological indicators. The percentage of water samples from water supply systems (water before entering the distribution network) that did not meet sanitary and chemical requirements was 17.15%. The expanding list of drinking water contaminants is forcing researchers to expand the range of methods for studying water safety. The article examines the question – is there really difference between the quality of bottled water, water purified by household water devices and tap water. The application of the biotesting method using Daphnia as test objects is considered as an assessment method. The complex toxicity index of water samples obtained by its additional purification with seven types of cartridges (filters) at different stages of cartridge resource is analyzed. The results showed that the toxicity of water depends on the cartridge used and the stage of its resource development. The practical significance of the work lies in demonstrating the impact of STBs on water safety and developing recommendations on their use to ensure high-quality drinking water. The results can be used to optimize water assessment methods and develop new standards for household filters.

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