One of the major challenges that populations have to face is vulnerability to water: lack of water, flooding, pollution, hazard sensitivity and coping capacity. For the reason of economic, social and environmental inequalities, this paper focuses on water-related vulnerabilities in the Metropolitan Region of Santiago (RMS) in Chile. Our main objective is to understand, through mapping, the multiscalar logics of water vulnerability. This study is carried out at two scales: at the regional level (RMS), we proceed with open access municipal statistical data and maps, while at the local level, a more detailed analysis focussing on the Chacabuco Province is based on the same type of data but with either a higher spatial resolution (Census districts) or a spatially more intensive data processing in order to take into account intra-municipal differences. In this way, we put into perspective the discourse developed in the Chilean media and by the inhabitants of Chacabuco Province regarding the province as an environmental 'sacrifice zone' for the RMS. The vulnerability maps are carried out at different scales in a simple and reproducible way by multi-criteria evaluation (MCE). The results confirm the hypothesis of a sacrifice zone and show that high-resolution data and adequate data processing give, on average, lower vulnerability scores than using only statistical data on the municipal level. The results provide a cartographic decision support for stakeholders. Limitations of the study are discussed and required further research pointed out.