Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to:

• Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amount of excess irrigation to avoid soil salinity
• Leaching (chemistry), the process of extracting substances from a solid by dissolving them in a liquid
• Leaching (metallurgy), a widely used extractive metallurgy technique which converts metals into soluble salts in aqueous media
  • Dump leaching, an industrial process to extract metals from ore taken directly from the mine and stacked on the leach pad without crushing
  • Heap leaching, an industrial process to extract metals from ore which has been crushed into small chunks
  • Tank leaching, a hydro metallurgical method of extracting valuable material from ore
  • In-situ leaching, a process of recovering minerals such as copper and uranium through boreholes drilled into the deposit
• Leaching (pedology), the loss of mineral and organic solutes due to percolation from soil
• Bioleaching, the extraction of specific metals from their ores through the use of bacteria and fungi