In March 2007, when Cryptosporidium contaminated water supplies in Galway City, Ireland, political authorities responded quickly to upgrade water treatments plants. This response framed the crisis as a solely technical problem of infrastructural decay, obscuring legacies of urban and agricultural (over)development. In this paper, we examine dominant responses to infrastructural contamination that depoliticize and re-inscribe divisions among bodies, nature, infrastructure, rural and urban. The temporality of the Galway outbreak and the speedy response by the state is not replicated throughout Ireland. In parts of rural Roscommon, the neighbouring county to Galway, microbiological risks to the drinking water supply have been left unattended for more than eight years. The interplay of social, political, economic, and ecological factors produces uneven exposures to health risks that are situated within and mediated through water infrastructure. Drawing on postcolonial insights, the unevenness of infrastructural provision across Ireland does not just tell a story of exclusion and othering, but also provides space for different infrastructural projects to unfold. While the response to contamination within the public water supply replayed well-known technical fixes, the work of the National Federation of Group Water Schemes, the representative body of community managed water systems in rural Ireland, illustrates a different form of infrastructural practice that negotiates legacies of institutional abandonment and acknowledges the wider hydro-social cycle as part of, rather than ancillary to, water infrastructure. By blending political ecologies of health and postcolonial approaches to infrastructure, we analyse the unevenness of responses to infrastructural contamination and trace its relationship to legacies of uneven development and imaginaries of urban and rural Ireland