Dependence of drinking water quality on the trophic status of the drinking water source

Introduction. Due to the climate change and increased anthropogenic impact, a gain in the number of eutrophic water bodies is expected, which may affect the quality of drinking water. Currently, the hygienic assessment conducted for selection of domestic and drinking water sources neglect their ecological state.

The aim of the study. To compare the composition of water in the water source with that of treated water using various trophicity and pollution criteria.

Materials and methods. We have analyzed physicochemical characteristics of surface and treated water in different seasons over a three-year period. The trophicity and pollution of the water source were assessed in accordance with the criteria available in literature. We used the canonical discriminant analysis to evaluate the forecast for assigning quality and safety indicators of the water source to trophicity and pollution types.

Results. We revealed seasonal changes in the levels of nitrogen forms and dissolved oxygen in the water source. We also established the seasonal excess of maximum allowable concentrations (MAC) for BOD5 (1.5 times), COD (1.1 to 3.8 times), and dissolved oxygen (2.0 to 2.9 times) in the water source and for permanganate index (1.1 to 2.0 times) and turbidity (1.2 to 2.6 times) in treated water. The trophic status of the water source was oligotrophic, mesotrophic, and eutrophic; the pollution level varied from very clean to dirty. In case of oligotrophy of the water source, the permanganate index in drinking water demonstrated a 1.1-fold excess of the MAC. The ecological type of water source characterized as very clean (in terms of mineral nitrogen) or oligotrophic (in terms of BOD5) did not meet the established criteria for water quality and safety.

Limitations. This study has no limitations.

Conclusion. The system of water quality and safety assessment should include trophicity indicators and components associated with biological processes occurring in water sources.

Compliance with ethical standards. This study does not require the conclusion of a biomedical ethics committee or other documents.

Contribution:
Khlystov I.A., Gurvich V.B. – study conception and design, draft manuscript preparation and editing, bibliography compilation and referencing;
Kharkova P.K., Novoseltseva E.E., Samylkin A.A. – data processing, bibliography compilation and referencing;
Shtin T.N., Kondakova L.V. – data collection and processing;
Sakhautdinova R.R. – draft manuscript preparation and editing;
Shevchik A.A. – statistical data analysis.
All authors are responsible for the integrity of all parts of the manuscript and approval of its final version.

Conflict of interest. The authors declare no conflict of interest.

Funding. The study had no sponsorship.

Acknowledgment. The authors express their gratitude to V.G. Panov, the senior researcher of the Department of toxicology and bioprophylaxis for help in statistical processing of data.

Received: July 7, 2025 / Accepted: October 15, 2025 / Published: November 14, 2025

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