The purpose of our study was to investigate the biofilm formation by Legionella pneumophila serogroup1 and serogroup2-15 on plumbing materials mostly used in building water systems in Morocco. The effect of plumbing materials and temperature were examined. The Atomic Force Microscopy was used to evaluate the roughness and surface topography of the plumbing materials including galvanized steel, stainless steel, copper, Polyvinyl chloride, Polypropylene Random Copolymer and Cross-linked polyethylene. Galvanized steel surfaces supported higher numbers of bacterial cells than that the stainless steel and plastic materials at 37 than 20 and 45 degrees C. Non-viable counts could be obtained from the copper surfaces. L. pneumophila sg2-15 strains presented a higher ability to biofilm formation than L. pneumophila sg1. The biofilm formation was evaluated by Atomic Force Microscopy.