This article analyses the relevance of investment protection rules as they relate to the remunicipalisation of water services. It describes why investor-state dispute settlement (ISDS) is deemed to be controversial and provides case-law examples. The article focuses on treaty provisions as they relate to the process of remunicipalisation, such as the fair and equitable treatment standard and specific clauses, and highlights where future challenges might come into play, such as environmental issues, which are directly or indirectly related to water scarcity or discussions of water as a human right. The role of municipalities, with regard to both the negotiations of free trade agreements (FTAs) and actual ISDS proceedings, is described. Analysis is accompanied by concrete advice for local actors and communities, demonstrating how challenges for remunicipalisation can be addressed, with regard to both existing FTAs and future negotiations of trade agreements.