This paper describes the ways that households, and particularly women, experience water scarcity in a large informal settlement in Nairobi, Kenya, through heavy expenditures of time and money, considerable investments in water storage and routinized sequences of defer red household tasks. It then delineates three phases of adaptive water and social engineering undertaken in several informal settlements by the Nairobi Water Company in an ongoing attempt to construct effective municipal institutions and infrastructure to improve residential access to water and loosen the grip that informal vendors may have on the market for water in these localities.