Polyethylene degreasers for animal and vegetable oils. The degreasers are intended for holding edible oils. These degreasers are made entirely of polyethylene and are of the vertical type and sized from 1 inhabitant equivalent up to 250 inhabitant equivalents. The grease separators have a smooth surface with a high thickness or corrugated surface, designed to appropriately resist backfilling operations. The grease separators have provisions for sewage inlet and overflow. In the upper part there