Microbial contamination remains the most common hazard threatening water quality. Microorganisms that emerge as a source of water-borne infection are human pathogens. The level of contamination of the water environment and the resurgence of water-borne diseases are also linked to environmental factors. It is in this perspective that the present work studies the effects of some environmental factors on the occurrence of some germs isolated from surface water in Maroua. The water was taken from the temporary rivers (Mayo): Kaliao, Palar and Lougueyo. In the laboratory, the germs isolated were bacteria, yeasts and microscopic fungi. The abiotic variables measured were pH, temperature, fluorine and chlorine levels. The variations of these parameters were induced in microcosm and the cultures were remade to test the variabilities of the germs isolated beforehand and the total abundance. Of the 20 microorganisms (16 bacteria, 2 yeasts and 2 fungi) isolated, 8 (Acinetobacter spp, Klebsiella spp, Enterobacter spp, Helicobacter spp, Legionella spp, Pseudomonas spp, Staphyloccocus spp, Streptoccocus spp) ont donné des cultures positives pour les conditions optimales des facteurs abiotiques simulés : température à 50 °C, pH entre 3,5 et 14 UC ; teneur en chlore à la concentration de 2 mg/L). Ces souches isolées de l’eau sont peu sensibles aux variations abiotiques. Les déterminants abiotiques comme, la température, la conductivité électrique de l’eau, la salinité, la nature et composition chimique du sol, sont des éléments à considérer dans le processus de désinfection de l’eau.  La maîtrise de ces facteurs rendrait les stratégies de contrôle des épidémies de maladies hydriques plus efficaces. 

Mots clés : Facteurs abiotiques – Microcosme – Microorganismes – Eaux de surface – Maroua