This paper introduces a model describing the full financial realities of FSM projects; a methodology for quantifying the costs, direct effects, and economic spillover effects; and a toolkit (under development) to calculate their net present values and the overall program’s internal rates of return. Understanding the economic spillover effect values offers innovative policy options for local decision makers to accelerate citywide FSM. Fecal sludge management (FSM) is implemented to transport fecal waste from residential environments, improve wastewater systems, and reduce the spread of pathogens and organic matter from human waste. The economic spillover effect describes ancillary benefits of citywide sanitation improvement programs for a community, including (i) increased property values, (ii) improved tourism and livelihood opportunities, and (iii) improved health and productivity.