Water has always been a driver of human civilization. The first human civilizations thrived in places with an abundance of water, typically nearby large rivers as the Tigris–Euphrates, Yang Che and Nile. The invention and construction of hydraulic infrastructure came only later, in prehistoric times, triggered by the expansion of humanity in water-scarce areas. The ancient Greeks invented impressive hydraulic works and small-scale structures, some of which, such as cisterns, were still fully operational until the 20th century. We present a model that explains the use of cisterns in the water-scarce area of West Mani, which allows us to assess the potential of this traditional rainfall harvesting practice to support the modern water supply needs. To assess the system’s reliability, we employ a long-term simulation of a typical cistern system, using synthetic rainfall series from a stochastic model, and assuming variable water demand on a monthly scale. We show that a proper restoration of the cisterns could be sustainable as a complementary water supply source, decreasing the area’s drinking water cost and increasing the locals’ resilience against water shortages. In addition, we highlight the links between the area’s hydroclimate and its history and discuss the cultural merits of reviving and preserving this ancient, long practice.