Calyx Global rates more than 30 types of carbon credit projects for greenhouse gas (GHG) integrity and, where certified, also for Sustainable Development Goal (SDG) contributions. Safe drinking water projects often receive both ratings. These projects reduce emissions by replacing a baseline practice of boiling water for disinfection with lower-emitting water treatment options. Safe drinking water projects also contribute to a range of sustainable development goals. Below, we outline key characteristics of this project type from a GHG and SDG perspective, and offer a preview of our first rating—a Tier 1 rating for credits from a water purification project in Togo.