Tapping the Markets: Opportunities for Domestic Investments in Water and Sanitation for the Poor presents the results of a detailed examination of market opportunities for the domestic private sector in the provision of piped water and on-site sanitation services in rural and semi-urban areas and of the commercial, policy, and investment climate factors that affect the response to these opportunities. It is based on case studies conducted in Bangladesh, Benin, Cambodia, Indonesia, Peru, and Tanzania. The results of focus group discussions with poor households, surveys of enterprises that directly serve poor households, and analysis of the supply chains that support them provide insights into the nature of demand for services, the prevailing business models of enterprises, and the impact of policy on decisions to invest or expand operations.