The Checklist aims to assist governments and their partners in facilitating the development and management of infrastructure with a view to increasing sustainable access to safe and reliable drinking water and proper sanitation facilities. The focus, therefore, is mainly on developing and emerging countries, where extending the relevant infrastructure constitutes a major challenge. High-income countries also face substantial investment needs in order to maintain and replace ageing networks but the issues and conditions differ depending on the level of development. These differences are most notable in the areas of institutional and regulatory framework development and level of access to water and sanitation. Nevertheless, the practices of OECD countries are presented when relevant, as they provide useful insights on issues at stake and possible policy responses.