Overview

• A Nature Water analysis of more than 15,000 facilities estimates U.S. wastewater treatment emits about 47 million metric tons of CO2e annually, roughly 41% above current federal inventories.
• The study attributes about 41% of sector emissions to methane and 24% to nitrous oxide, underscoring that on‑site biological processes dominate the climate footprint.
• A Princeton-led mobile field campaign at 96 plants found methane about 2.4 times and nitrous oxide about 1.9 times higher than EPA estimates, with plants contributing an estimated 2.5% of U.S. methane and 8.1% of nitrous oxide emissions.
• Researchers report that a relatively small subset of facilities drives most emissions, indicating targeted improvements could deliver outsized reductions without an industry-wide overhaul.
• Operational fixes such as repairing anaerobic digester leaks and rethinking nitrogen removal are being pursued as teams work with utilities and refine open‑source tools to map and cut emissions.