The promotion of responsible consumption is a key strategy to achieve environmental benefits, sustainable food security, and enhance public health. Countries like Spain are making efforts to reverse growing obesity and promote healthy diets, such as the recommended and traditional Mediterranean, recognized as a key strategy to improve the population's health with locally grown, traditional, and seasonal products like fruits, vegetables, olive oil, and fish. With a view to connecting water, agriculture, food security, nutrition and health, this research aims to investigate and compare the nutritional and water implications of the current food consumption of Spanish households with the recommended Mediterranean diet. Besides, we calculate their nutritional composition, compare their water footprints, and develop a new methodological approach to assess nutritional water productivity (i.e. the nutritional value per unit of embedded water). Results show that the current Spanish diet is shifting away from the recommended Mediterranean towards an alternative one containing three times more meat, dairy and sugar products, and a third fewer fruits, vegetables, and cereals. The Mediterranean diet is also less caloric, as it contains smaller amounts of proteins and fats and is richer in fiber and micronutrients. Due to the high-embedded water content in animal products, a shift towards a Mediterranean diet would reduce the consumptive WF about 750 l/capita day. Additionally, the Mediterranean diet has better water-nutritional efficiency than the current one: it provides more energy, fiber, and nutrients per liter of consumptive water. The study confirms the Mediterranean diet is a healthier and more sustainable diet with strong cultural heritage.