This study quantifies the water footprint of consumption (WFcons) and production (WFprod) of Milan. The current WFcons amounts to 6,139 l/cap/d (a volume of 2.93 km3 annually), of which 52 l/cap/d (1%) is attributed to domestic water, 448 l/cap/d (7%) to the consumption of industrial products and 5,639 l/cap/d (92%) to the consumption of agricultural products. The WFprod is 52 l/cap/d. Milan is thus a net virtual water importer, predominately through the import of agricultural products. These are produced outside city borders, both in Italy and abroad. This shows the dependency of city dwellers on water resources from other river basins. In addition, the WFcons for a healthy diet (based on Mediterranean Food-Based Dietary Guidelines) and a vegetarian diet are analysed. The current Milanese diet consists of too much sugar, crop oils, meat, animal fats, milk and milk products and not enough cereals, rice, potatoes, vegetables and fruit. The latter two diets result in substantial WFcons reductions: −29% (to 4,339 l/cap/d) for a healthy diet and −41% (to 3,631 l/cap/d) for a vegetarian diet. Indeed, a lot of water could be saved by Milan citizens through a change in their diet. A sustainable city should account for its impacts beyond its borders.