In France, municipalities and inter-municipal bodies are the primary actors for drinking water supply and sanitation, while regional and departmental bodies as well as irrigation groups are in charge of aquifer and river management. Who implements central government water policies at the sub-national level? A first category includes countries where implementation of water policies at the sub-national level essentially relies on a single type of actors, i.e. representatives of central government in regions, and a second category includes countries with a combination of several sub-national authorities’ responsibilities in the implementation stage. This often, if not invariably, reflects how decentralised water policies have become across OECD countries.