This paper examines how the law governing water has evolved in the United States and Australia. The evolution of water law in these jurisdictions demonstrates that the ‘scientific modernism’ that prioritises economics and hydrology as the pivots around which water institutions are designed may be an incomplete model. From the history we recount, we suggest that, ranking equally with these considerations in shaping water law and policy, is the broader framework of laws and institutions, and legal culture within a society. These factors shape the types of solutions to conflicts in a society and determine, to a substantial degree, the solutions to water conflicts that become law, which then in part determine future legal solutions. This observation is of more than theoretical importance. Towards the end of this paper we consider the latest water modernist experiment, the Australian Water Act. We suggest that closer attention to social factors and legal traditions would have resulted in a more effective law. We believe this holds important lessons for water policy generally.