California's state constitution prohibits the “wasteful” use of water; however, waste is subjective and context dependent. This paper considers political, biopolitical, and material dimensions of waste, focusing on the role of legal processes and institutions. The paper examines a case involving legal accusations of “waste and unreasonable use” of water by the Imperial Irrigation District in Imperial County, California. The determination that water was being “wasted” justified the transfer of water from agricultural to urban areas. However, defining these flows of water as a waste neglected water's complexity and relationality, and the enclosure of a “paracommons” threatens to bring about negative environmental and public health consequences. The paper shows that the project of discursively labeling certain material resource flows as waste and re‐allocating these resources to correct this moral and economic failure relies upon legal processes, and carries political and biopolitical implications.