Effective water management and policy play a critical role in shaping society’s evolving relationship with water. Yet, the growing impacts of water-related risks worldwide show that many responses remain ineffective, often leading to unintended consequences that undermine stated policy objectives. These contradictions—referred to in the literature as water paradoxes—occur when well-intentioned efforts to manage water backfire. This Review argues that researchers should better characterize these paradoxes, and practitioners must integrate them in decision-making processes and economic evaluations of water policy.