Roads are generally perceived as infrastructure to deliver transport services, but they are more than that. They are major interventions in the hydrology of areas where they are constructed - concentrating runoff and altering subsurface flows. At present, water-related damage constitutes a major cost factor in road maintenance. Using ongoing research from Ethiopia, this article argues to reverse this and turn water from a foe into a friend and integrate water harvesting with road development. Optimized road designs are required - better planning of alignments, making use of road drainage, road surfaces, and river crossings, but also capturing freshly opened springs and systematically including developing storage and enhanced recharge facilities in road-building programmes. Equally important are inclusive planning processes that are sensitive to the multi-functionality of roads but also to the potentially uneven distribution of benefits and the diverse livelihood impacts. There is a need for closer integration of watershed and road-building programmes. With 5.5 million kilometres of roads in sub-Saharan Africa alone, and road building continuing to be one of the largest public investments, the potential of roads for water harvesting is great.