Conducting an accurate hydrological water balance at the regional and country-wide scales is paramount to assessing available water resources and adequately allocating them. One of the main components of these balances is the anthropogenic recharge of groundwater either intentionally, through managed aquifer recharge (MAR), or unintentionally, where infiltration from dams and dykes can play a significant role. In Spain, proper management of water resources is critical due to the arid to semiarid conditions prevalent in most of the territory and the relevance of water resources for maintaining a robust agricultural sector. Spanish Previous work has estimated country-wide recharge from MAR at 150-280 Mm3/year. Recently, water authorities have pointed out that, according to hydrological water balances, the total volume from "unintentional recharge" from water courses may exceed 500 Mm3/year. The present research aims to present a new inventory of transverse structures in Spain and use it to estimate country-wide unintentional recharge. The inventory, compiled by the Spanish Ministry for the Ecological Transition and the Demographic Challenge, has more than 26,000 structures and includes construction characteristics, which allow for estimating the wet perimeter and the infiltration area. Structural data from the inventory was crossed through map algebra with thematic layers, such as lithology, permeability, the digital elevation model, the average groundwater levels, etc., in a GIS environment to arrive at the objective. Different analytical formulas to compute infiltration from small dams and dykes were also employed. The resulting volume of unintentional recharge from transverse structures in Spain is about 800 Mm3/year. This quantity can help close the hydrological balance at the national and river basin levels. Furthermore, this figure provides an order of magnitude for anthropogenic recharge at a national scale, which is difficult to obtain.