For decades, the discharge of waste water from a landfill has been synonymous with leachate. But what is it? Simply put -it’s any contaminated liquid that’s created when rainwater filters through solid-waste disposal sites like those found within urban areas or on agricultural lands; organic and inorganic substances are both present within these mixtures (which can be highly toxic) meaning they pose potential risks for pollution not only to land but also ground waters as well aquatic environments .