The wide circulation of Klebsiella bacteria in water ofwater objects of different climatic zones of Russia and various function is established. So bacteria of the Klebsiella strain are in superficial sources of the centralized water supply depending on extent of their biological and chemical pollution; underground waters at the unprotected water-bearing horizons; in drinking water at insufficiently effective system of its cleaning and disinfecting. Klebsiella circulating in water was shown to keep properties of pathogenicity and a virulence, possess resistance both to modern preparations and disinfecting agents (chlorine, an ultraviolet to radiation). Bacteria of the Klebsiella strain have high penetration in the water-bearing horizons. At strains of Klebsiella there is allocated considerable pathogenic potential (adhesive, invasive, phosphatase, lecithinase, DNA-ase, hemolytic activity) and genetic markers of pathogenicity of cnf-1. The etiologic role of bacteria of Klebsiella and an infecting (100, COE/dm3) dose emergence of acute intestinal infections (AII) is established. Detection of Klebsiella in water objects and especially in water of drinking appointment, in the absence of total coliform bacteria (TCB) contributes to the epidemic danger of water use.