Abstract: A cover for water flow inlet for rainwater drainage of roof and buildings is disclosed. The inlet cover comprises an outer formation forming a plurality of ridged fins to avoid the vortex formation of rainwater entrainment and to protect the cover from debris materials and a central plate member. The central plate member has a profiled lower surface. The plate member is of an inverted shape with a plurality of ridged formation or channels on the lower surface to further eliminate formation of air inducing and vortices, therefore promoting high volume laminar flow of water in the inlet pipe of the drainage system.