What is water? This ontological inquiry bares various answers. One of them is offered by the hydro-social cycle, a conceptual framework that views water and society as co-constitutive, relationally entangled entities. Drawing on foundational contributions from political ecology and geography, this chapter traces how the hydro-social approach emerged as a response to nature–society dichotomies. Rather than treating water as a passive object, or resource, this perspective sees it as a socio-natural hybrid, continually produced and transformed through its entanglement with infrastructures, discourses, institutions, and power relations. Yet, the chapter interrogates the paradigm’s limitations, including theoretical eclecticism, anthropocentric tendencies, and insufficient methodological clarity. To address these issues, it turns to Bruno Latour’s ontological politics, rethinking water not merely as a hybrid but as part of collectives where human and non-human actors share potential agency. It proposes a ‘water parliament’ model to institutionalise plural definitions and stakes. Building on this, the chapter introduces controversy mapping from Science and Technology Studies as a methodological intervention. Their goal is to trace and visualise how competing ontologies of water emerge, circulate, and stabilise across actor–networks. Later applied to the Lake Urmia case, this approach surfaces the political, ontological, and empirical dimensions of water governance.