Water is a key resource to agriculture in Mendoza but there are increasing concerns regarding the viability of current practices and availability. Some farms fall short of their production potential, which questions the economic viability of some vineyards, and might trigger structural change and lead to additional pressure on water use. Improvements in irrigation efficiency could help mitigate this problem. Farmers pay for the resource management but do not have to consider the opportunity cost of the resource itself. This paper estimates the technical efficiency (TE) of grapevine production controling for the use of water. The preliminary results point out average efficiency scores of 0.78, where relatively efficient farmers lack proper management practices on water resources. Further estimation of the intrinsic value of irrigation water will provide an additional tool to design specific policies for the sector.