The excreta of more than half of the world's population is discharged into the environment without treatment of any kind. Particularly in low- and middle-income countries with limited public finance for treatment infrastructure, resource recovery from wastewater has the potential to finance part of the costs of sanitation systems. Most assessments of resource-recovering treatment systems in low-income settings have focused on their technical performance. In this study, using data collected from 14 upward-flow anaerobic sludge blanket septic tanks in rural Panama, we estimate the proportion of waste treatment system costs that could be offset by biogas sales. We find that biogas revenues would cover between 26% and 49% of system operation and maintenance expenses, and would improve the net present value of the wastewater system investment by 8% to 15%. Aggregate stated demand for in-home biogas delivery among sample households is more than twice the volume of gas that could be generated by a system treating waste from the entire community. In Panama and other countries where public resources are devoted to subsidizing liquid propane gas, investment in wastewater treatment systems with biogas recovery could reduce the cost of energy provision to households while improving public and environmental health.

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