Abstract Background With the planetary crisis comes an increasing risk of flooding events. As shown during the 2021 floodings in Limburg, these can have disastrous consequences for the public health system and healthcare organisations. Historically flooding events are often treated as either affecting public health or acute care, but the 2021 events showed the necessity of an intersectoral governance approach. In this study, we investigated how governance actors from different domains collaborate and perform shared sensemaking processes to ensure patient safety continuity of (public health) care. Methods For the past months, we conducted a qualitative case-study in the Dutch region of Limburg where we interviewed governance actors from public health, acute healthcare, water management, and safety and crisis management. We also observed and analysed crisis exercises and hospital crisis management meetings, including relevant paper trails. All data were abductively coded and thematically analysed. Results Our analysis shows that during and after the flooding event, actors were confronted with numerous vulnerabilities about decisions to evacuate hospitals, care homes, or even villages. These include decisions about what are public health risks, and what are not. To curb such uncertainties, intersectoral sensemaking proofed essential with a central role for the public health crisis system. In our presentation we highlight how such sensemaking was done in practice. Conclusions To deal with the effects of the planetary crisis on healthcare, events such as floodings must be approached intersectorally. The public health system plays a central role in perceiving the vulnerabilities in a crisis from all angles. Key messages • Floodings are more likely to affect the public health and healthcare system. • Highly complex crises, such as floodings, require an intersectoral governance response with the public health system in a central role.