Abstract
Coliphages are bacterial viruses that have been tested for many years to dermine their usefulness as indicators of faecal contamination and presence of human viral pathogens in water. Retrospective analyzes of water-borne outbreaks have shown that E. coli tests are not enough to assure the safety of water intended for human consumption. Coliphages are more resistant to disinfection in comparison with bacterial indicators and are able to survive at considerable distance from source of contamination. Using of coliphages as indicators, to ensure better control and safety of drinking water had been recommended by WHO experts and introduced in Directive (EU) 2020/2184. Somatic coliphages are new indicators of water microbiological quality assessment, including indication of intestinal viruses. They can be used to verify processes of water treatment and to assess efficiency of removing intestinal viruses.