Aqua Nullius: First Nations Water Rights in Australia applies the logic of terra nullius to water, naming and challenging the fiction that Australia’s waterways existed without sovereign custodians — and lets more than twenty First Nations voices dismantle that claim directly. Structured around four interlocking themes — storytelling, water injustice, First Nations water management, and overturning aqua nullius — this book assembles over twenty interviews with First Nations people from across Australia whose relationships to water are as old as the land itself. It is not a policy document or an academic treatise alone; it is a record of custodianship, grief, and authority. For architects, landscape practitioners, and planners working on Country, it reframes water not as infrastructure or resource but as kin, as law, as living system. Published by OFFICE, it arrives as an urgent contribution to conversations about Indigenous water rights and sovereign knowledge in Australia.