Risk-based governance is argued by many to hold the promise of a more rational and efficient state, by making explicit the limitations of state interventions and focusing finite resources on those targets where probable damage is greatest. This paper challenges the assumption that risk-based governance has the potential for universal and uniform application, by comparing contemporary flood management in Germany and England. On first inspection, flooding appears to be a paradigmatic case of risk colonizing European policy discourses, with the traditional notion of flood defense giving way to flood risk management in the context of climate change, increasingly frequent flood disasters, political and cost pressures on flood protection, and publicly available European-wide flood assessments. Drawing on in-depth empirical research, this paper shows how the role, and even the definition, of “risk” is institutionally shaped, and how the respective institutional environments of German and English flood management practices impede and promote risk colonization. In particular, the use and conceptualizations of risk in governance are variously promoted, filtered, or constrained by the administrative procedures, structures, and political expectations embedded within flood management and wider polities of each country. The findings of this research are important for the design and implementation of supranational policies and regulations that endorse risk-based approaches, such as the recent EU Flood Directive, as well as scholarly debate as to how to legitimately define the limits of governance in the face of uncertainty and accountability pressures.