Abstract: Water law in Australia is underpinned by the erroneous assumption of aqua nullius, the attempted extinguishment of Indigenous water laws. It’s not a situation unique to Australia as similar processes have occurred in all settler colonial states. In doing so, the state is assuming the power and authority to control and usually exploit water that it does not legitimately have. This means that the foundation of settler state water law is basically rotten at the core. It’s not just unfair, in Australia this injustice lies at the heart of decades of failed water policy. The Australian Government has just passed new laws which hopefully mark the first steps in redressing this situation, and has another important opportunity in the new EPBC Act reforms in 2024. Here, Erin O’Donnell, Melissa Kennedy and Janice Baird explain why this reform is so important and what needs to be done if aqua nullius is to be finally overturned.