Waste Metalworking Fluids are generally classified as hazardous waste since usually they consist of oil, biocides, fines and swarf. Hazardous waste cannot be disposed of directly in landfill sites. In line with the European requirements, hazardous wastes must be treated to reduce their hazardous properties before they are landfilled. Any producer of hazardous waste must work with their disposal contractors to ensure that the waste is properly segregated and treated so that the environmental impact of the waste is minimized.

EEF, the manufacturers' organization, helps explain this in details.