When wasted food is sent down the drain, it combines with other wastes in the sewer system and ends up at a water resource recovery facility, or wastewater treatment plant. Sending wasted food down the drain is one of the least preferred pathways because wasted food decays rapidly in the sewer system and generates methane, a powerful greenhouse gas.  Methane emissions from sewers are released directly into the atmosphere.

Energy is required to treat wastewater that contains nutrient-rich wasted food. Depending on the operations at the water resource recovery facility, the valuable nutrients in wasted food may not be recovered for beneficial use. Even if a facility recovers energy through anaerobic digestion, the recovered energy does not offset the methane emissions from wasted food in sewers and extra energy demand for wastewater treatment.

Published by the EPA | October 2023