In the context of globalizing transboundary environmental challenges, strategies to protect and secure the local commons such as water resources have been increasingly scaled up. Consequently, local communities have started to engage in transnational mobilisations to defend their rights and express their concerns. This often implies the adoption and institutionalisation of emerging global norms, principles and modes of framing and claiming – such as the Human Right to Water or the Rights of Nature – which will interfere with and may even go against local understandings, meaning, and rooted struggles or initial claims made by grassroots movements. On the one hand, the appropriation of expert knowledge and technical idiom may improve their recognition and access to political and financial support. On the other hand, transnational involvement may (re)produce misrecognition or exclusion on the ground for community-based organisations. Studying cases from Latin American countries, and combining commons and social movements theories, this paper examines in what ways professionalisation and commensuration strategies as deployed and implemented by transnational grassroots movements impact the local commons.