The invention describes a method for manufacturing a plastic drain sheet, and a plastic drain sheet. For the purpose of manufacture, a sheet-like main body having a first surface and a second surface, spaced apart therefrom by a base sheet thickness, is provided. Grooves are introduced into the first surface and mating grooves are introduced into the second surface. The mating grooves and the grooves cross one another at crossing points. Through-openings between the grooves and the mating grooves are formed at the crossing points.