Water, as a common pool resource, is threatened by the possibility of overextraction gen-erating a negative economic impact, conflicts among users, and greater income inequality. Scholars have discussed different governance approaches to deal with this threat, including centralized governance and self-governance, and lately, special attention has been paid to the interactions between formal institutions (the state) and local water user associations and how this promotes self-govern-ance. The aim of this paper was to examine the adoption of Ostrom’s design principles present in the legal norms dictated in the Chilean Water Code by water user associations and to analyze the roles of their size, community homogeneity, and perceived water stress on adopting legal norms. The results showed that water communities generally follow the rules established in the Water Code, but the voting system, distribution of water, and fee payment are adjusted in small and ho-mogenous water user associations. We can also conclude that a cornerstone in the system is implementing graduated sanctions, as water users see the tools provided by the Water Code as ineffec-tive.