Hygiena 2026, 71(2):60-65 | DOI: 10.21101/hygiena.a1905

An unusual case of visible live larvae in drinking water

František Kožíšek

Státní zdravotní ústav, Centrum zdraví a životního prostředí, Oddělení hygieny vody, Praha, Česká republika

In the fall of 2025, an emergency situation occurred in the local water supply system in a small village in the Moravian-Silesian Region, after which some consumers began to randomly find small particles visible to the naked eye in their drinking water, including living organisms (e.g., midge larvae). Laboratory analyses repeatedly but irregularly found coliform bacteria, so a replacement supply from cisterns was introduced. As the operator was at a loss as to how to deal with the situation, after a month of problems, he turned to the National Institute of Public Health (NIPH) for help in identifying the cause and advising on a remedy. The NIPH determined the cause after an on-site investigation. The article describes the emergency event and the mechanism of contamination, the method and results of the on-site investigation, the health risk, and the proposed remedial actions to solve the problem.

Keywords: drinking water contamination, drinking water - living organisms, drinking water supply, accident

Received: February 2026; Accepted: February 2026; Published: June 2026  Show citation