Qanats are a traditional technique used for aquifer water acquisition and irrigation in dry lands, common to the Middle East. They provide fresh water to communities of users by draining groundwater from aquifers. In Iran, authorities are reporting about 37,000 active qanats contributing about 11% of the country's total ground water supply. Yazd Province, located in the central part of Iran's plateau, is among the driest regions of the country with more than one million people. It counts 3,193 known qanats with an annual discharge estimated today at about 350 million m3. Ghassem Abad qanat irrigates the agricultural lands of Ghassem Abad village in the Province of Yazd. Its water is managed by an administration headed by a mirab. This paper describes the qanat's mechanism and provides an overview about qanats in Iran. It also promotes, through the study of Ghassem Abad qanat, the related water management system as an example of eco-friendly traditional knowledge leading to social equity and sustainability. It explains how water is distributed to stakeholders (through water shares and irrigation cycles). Nevertheless, and for its survival, the qanat of Ghassem Abad has to continuously deal with social and economic challenges. The farmlands are continuously menaced by urban expansion.