Liquid waste. Liquid waste can be defined as wastewater, fats, oils or grease, which is fog used oil, liquids, solids, gases or studies and hazardous houses. Household liquids. These liquids that are hazardous or potentially harmful to human health or the environment. They can also be discarded commercial products classified as liquid industrial waste, such as cleaning fluids or pesticides, or the byproducts of manufacturing processes. There are general regulatory requirements relating to waste