Organised around the 24 OECD Principles for Private Sector Participation in Infrastructure, this Checklist for Public Action aims to help governments wishing to engage the private sector in the development and management of water and sanitation infrastructure. For each Principle, the Checklist lists the key specificities of the water and sanitation sector; the corresponding issues for governments; and some available tools and country practices. It highlights five areas of key importance for consideration by governments: 1. Deciding on the nature and modalities of potential private sector involvement; 2. Providing a sound institutional and regulatory environment for infrastructure investment; 3. Ensuring public and institutional support; 4. Making the co-operation between the public and private sectors work in the public interest; 5. Encouraging responsible business conduct.