Since its origins, the life of Ajaccio is greatly punctuated by its relationship to water, whether it is potable or sea. The site of Saint-Jean is urbanized since antiquity not far from the banks of the river Arbitrone taking its source in the valley of Saint-Antoine which is long dedicated to agricultural activities. Drinking water became one of the concerns of the Republic of Genoa when the construction of the citadel began in 1492. Although the security problems of the city were partially solved, the lack of water quickly became apparent and represented a brake on the development of the city until Napoleon’s urban plan at the beginning of the 19th century. At the same time, commercial activity around the sea, whose wealth (coral, fish) is exploited. Even today, the Grande Bleue economy, now linked to tourism, remains at the centre of the local economy. Philippe Perfettini, animator of the heritage of the city of Ajaccio, will tell these stories of waters essential to the development of the territory.