Questionnaires were distributed in 3308 families divided into two groups: group 1 with no cases of acute intestinal infections and group 2 where such cases were registered. Information contained in the questionnaires was processes by means of computers bzsm-6. The analysis of the data on the occurrence of characteristics indicating the quality of water supply and water consumption (25 characteristics), sewage and sanitation (12 characteristics), living conditions (19 characteristics) showed that the living conditions of the families in group 2 were worse than those of the families in group 1. The occurrence of these characteristics in the families of patients with acute intestinal infections and in the families of carriers were mostly the same, and the existing differences in such characteristics as "fishing", "use of water from ponds for house-hold purposes" proved to be nonessential. The population of the city was divided into four risk groups with regard to the possibility of contacting infection, depending on the conditions of water supply, water consumption and sewage in different housing areas: the group registered as stable on account of sanitary and hygienic conditions, the groups of usual, increased and maximum risk.