This paper investigates the social life and material circuits of water in the Egyptian squatter settlement Izbit Kherallah in order to examine the role of water in urban ecologies and to understand the social pathways that water takes through city environments. The research was carried out over a sixteen-month period, from September 2009 through December 2010, in a six hundred acre squatter area located near downtown Cairo. It investigates how the role of water as a border zone, or “ecotone,” (Haraway 2008) between humans and other living and material forms in urban ecologies frames new questions about the nature of interspecies dependence and human cultural worlds (Thrift 2004; Mitchell 2002; Latour 2004; Gandy 2004, 2005; Tsing 2005; Haraway 2008). It looks at the ways in which a variety of city infrastructures, including physical, social, biological, and affective cycles, conjoin in water. Water is a key site in which to view the implications of human’s mutual constitution with a whole host of “others,” from the intense investigation of the domestic or microscopic biological interlocutors that Haraway proposes, to the meanings of our human connections to the built environment of cities that Nigel Thrift and Mathew Gandy suggest. In Izbit Kherallah, community members seek enough potable water to cook, drink, bathe, make wadu (which is the act of bathing particular body parts with water in preparation for prayer in Islam), and clean their homes. At the same time they also combat the effects of alternating periods of highly chlorinated water that causes kidney and liver issues, and water contaminated by sewage leakage that spreads communicable diseases such as hepatitis and intestinal worms. One key arena in human-nonhuman relationships is the stomachs of Izba’s youngest residents, as repeated exposure to contaminated water and food frustrate the attempts of mothers to keep their children healthy. Here, the project uses the idea of bodies as composites of various interdependent creatures ultimately necessary for each other’s survival to think through the permeability of bodily boundaries and their connection to larger water systems in which they are enmeshed. In sum, this project engages with how the lives of Izbit Kherallah residents coexist with cycles of water and the living things that move in and through it.