In this article I discuss the relationship that can be established between nationalism, as an ideology referred to the promotion and protection of a nation, with water, a natural resource that forms part of the national territory and, therefore, may be subject to national interests. To frame this approach, I chose the example of the Spanish State, which has a long experience in the exploitation of its water resources. I will focus on the period from the “98’s Disaster” until the end of Francoism in 1975. During this period, water was integrated in the ideological apparatus of Spanish nationalism as a vehicle for modernization, “regeneration” or national progress, an ideal that was materialized in the design and realization of new water policies oriented at the construction of dams and other infrastructure works with the objective to rearticulate Spanish society and economy.