The puquios of Nasca are a system of subterranean filtration galleries that provide water for irrigation and domestic uses in the middle portions of the Nasca, Taruga, and Las Trancas valleys of the Río Grande de Nasca drainage of the south coast of Peru. At present 36 puquios function in these three valleys; in the past their number may have exceeded 50. We discuss the formal characteristics and the construction of the puquios, and describe each of the extant puquios. The results of archaeological settlement surveys conducted in the three valleys indicate that the puquios did not yet exist in Early Nasca (Early Intermediate Period 2-4) times, but were almost certainly in use by the time of the Inka conquest of the region in the late fifteenth century. We suggest that the initial construction and use of the puquios may have occurred as early as Nasca 5 times, and probably not later than Late Nasca (Early Intermediate Period 6-7) times.