Connections between people and water have received considerable attention within geographic research. This paper draws on cultural and historical geographies, political ecology and the environmental humanities to extend understandings of the hydrosocial cycle by focusing on the cultural dimensions of society–water relations through the concept of shadow waters. Shadow waters centres attention on the cultures that privilege certain waters while rendering other waters invisible and marginalised. Inspired by Val Plumwood's notion of “shadow places”, shadow waters brings to light the way power intersects with cultural practices. We bring this concept of shadow waters into conversation with Indigenous water knowledges. Shadow waters can be conceptualised vertically, with surface water receiving more policy and research attention than ground water, and also horizontally, as some sub‐catchments, uses and values have been ignored or undervalued in macro‐catchment processes. Temporally, in considering the past, complex and contested histories of human–environment relations are often overlooked in favour of simple historical narratives that ultimately reinforce dominant management structures and trajectories. Shadow waters are thus historically created as particular power structures and narratives are reinforced and “normalised” over time. This paper examines shadow waters in southeastern Australia, elucidating the way two rivers are interwoven and co‐determined in cultures of water use in this context. We show how the rethinking of dominant water cultures, made possible by cross‐cultural engagement, generates new possibilities for reconnection, restoration and protection; a different water ethics based on care and responsibility that addresses power relations and injustices.