Jacques Derrida's Monolingualism of the Other is filled with attention to fluids: seas, shores, floods, canals, waves, rivers, and tsunamis all meander through and soak its pages. Against the metaphysical privilege of substance, I argue Derrida deploys these waters to clarify the role of différance, the failure of self-identity, and the relation between autobiography, land, and citizenship. Specifically, by attending to Derrida's discussion of water, I argue Monolingualism both questions the possibility of autobiography in light of the elemental nature of language and identity, and critiques colonial ontopological configurations that secure belonging through the solidity and fixity of land and borders (or border walls). Turning then to the U.S.-Mexico border, I use Derrida's liquid logic to clarify and problematize the way migrants and refugees are made intelligible as ontopological failures through their association with water and water metaphors (i.e., "flows" or "waves" of migrants "flooding" into the U.S.). Instead of advancing the phantasm of the solid—building dams to keep out migrants or opening the floodgates of U.S. citizenship—Derrida prompts us to track (and resist) flows of colonial state power, while affirming our fluid relations to language, community, and land, or what I am calling our agua-biographies.