In this paper, we use the notion of administrative precarity to refer to the vulnerability and insecurity experienced by marginalised and disadvantaged groups as a result of their interactions with ambiguous administrative procedures. Using the example of water infrastructure administration in Mumbai, specifically the experiences of ‘Pani Haq Samiti’– the ‘Right to Water campaign’– we formulate how administrative precarity and infrastructural violence intersect in transcalar practices of ambiguation in urban governance. We build on a nascent set of literature that illustrates how ambiguity in administrative processes is used as a tactic to avoid or deny the impacts of bureaucratic process of water and sanitation governance in Mumbai. We work through several examples of the ambiguous practices and paperwork involved in implementing the universal right to water in urban Mumbai with a specific focus on the challenges in non-notified slums. We demonstrate that the practices of ambiguation, are often entrenched in everyday interactions between citizens or activists and administrators on the ground. In enabling the continued withholding of water infrastructure these ambiguous bureaucracies create an administrative precarity and are thus constitutive to persistent infrastructural violence against marginalised groups. We show that everyday practices of activists and administrators provoke the labours of de-ambiguation as a pre-requisite to the implementation of infrastructural solutions to achieve the ‘Right to Water’ under administrative precarity. We call for more research on everyday practices of (de-)ambiguation, including highlighting the potentially transformative role that urban scholarship may take to support the labour of de-ambiguation.