What is the polluted water at the bottom of a landfill called?

The polluted water at the bottom of a landfill is called leachate. It is formed when rainwater or other liquids percolate through the waste materials, dissolving various chemicals and contaminants in the process. Leachate can be toxic and poses environmental risks if not properly managed. Landfills typically have systems in place to collect and treat leachate to prevent it from contaminating surrounding soil and groundwater.