The Tagus-Segura water transfer has generated significant value in the region that receives its water resources. Despite this value, some agents seek the cancellation of this important infrastructure, arguing economic, environmental, social, and political problems. With the aim of providing information on the efficiency of the Tagus-Segura aqueduct as a water resource management measure, especially in terms of the importance of water and the tariffs paid by the users of the aqueduct, this paper presents valuable information to analyse how to improve the functioning of the infrastructure. Thus, the southeast of Spain obtains a high return on the water received from the water transfer while covering all the financial costs derived from it. However, in 2017 a modification was introduced in the tariff that forced water users to cover the construction and fixed costs of the infrastructure as if the total amount of water agreed upon had been received, when in reality a lower amount had been received. This problem was not solved by the proposed tariffs for 2021, and it is therefore essential for the efficient operation of water transfer to modify these tariffs so that they are fair and reduce existing problems, thus avoiding the cancellation of an infrastructure that has not yet been amortised and which provides many benefits to the receiving region.