Water has important economic values, mainly in the agricultural sector. Beside enhancing agricultural output and crop diversification, irrigation generates positive externalities which have been little emphasized by the literature. The purpose of this review is to investigate the direct, indirect and potential
benefits of water use in agriculture by taking an additional step towards the identification and economic evaluation of the observed positive, social, environmental and ecological effects of irrigation. Five categories of contributions are examined: irrigation returns flows for groundwater recharge; biodiversity
and wildlife habitat; landscape aesthetic and cultural values; nutrient recycling and retention; and improved health, nutritionand living conditions. Knowing the economic value of such positive externalities would help to get the right policy incentives for better water use and increased water savings in a context of growing water scarcity.