Which liquid forms when rainwater or groundwater flows through decomposing waste?

• A. Seepage
• B. Leachate
• C. Cap
• D. Sludge

Answer: (B)

When moisture moves through decomposing waste, it picks up dissolved substances from the waste and becomes a contaminated liquid called leachate. This liquid can carry a variety of pollutants—organic compounds, salts, metals, ammonia, and other compounds—making it a major concern for groundwater and surface water protection unless it’s collected and treated properly. Seepage is a general term for water moving through soils and isn’t specific to waste-derived liquid. A landfill cap is the impermeable cover used to limit infiltration, not a liquid. Sludge is the semi-solid material produced from wastewater treatment. So the liquid formed specifically by rainwater or groundwater flowing through decomposing waste is leachate.