This study argues that by mobilising ‘social resources’, communities in water-scarce, semi-arid areas can not only successfully sustain a livelihood, but they can also play an important role in the water budget of their semi-arid regions. The pastoralist communities in the Darfur region of west Sudan utilise the limited volumes of green – root-zone – water in the soil to rear livestock. They have for centuries developed and adopted a very adaptive management system that has enabled them to utilise the green water of the Nile Basin. The embedded green water in livestock totals more than Sudan's annual share – 18.5 km3 – of the Nile River flow allocated to it by the 1959 Nile Waters Agreement. This study has revealed that this embedded ‘virtual water’ amounts to 37.6 km3. Results show that this silent, unrecognised, green water has been providing a solution to the water requirements of the Nile economies. It has been suggested that if Western Sudan's livestock were to be produced using fresh/blue water from the Nile, the national water balance of the Sudan would be very seriously impacted and the economy would be much less secure than it has been for the past half century.