IntroductionWater insecurity–the inability to access and benefit from affordable, reliable and safe water for basic needs–is a considerable global health threat. With the urgent need to target interventions to the most vulnerable, accurate and meaningful measurement is a priority. Households use diverse strategies to cope with water insecurity; however, these have not been systematically characterised nor measured. The Food Insecurity Coping Strategies Index has been insightful for targeting nutrition interventions to the most vulnerable. As a first step towards creating an analogous scale for water, this study characterises the largest empirical data set on water insecurity coping strategies and proposes guidance on measuring it using a novel toolkit.MethodsOpen-ended responses on water insecurity coping (n=2301) were collected across 11 sites in 10 low- and middle-income countries in the Household Water InSecurity Experiences (HWISE) Scale validation study. Responses were characterised and compared with behaviours identified in the literature to construct an instrument to systematically assess coping.ResultsWe identified 19 distinct strategies that households used when experiencing water insecurity. These findings, paired with prior literature, were used to develop a Water Insecurity Coping Strategies Assessment Toolkit with guidance on its piloting to assess coping prevalence, frequency and severity.ConclusionsThe widespread occurrence of water insecurity coping strategies underscores the importance of understanding their prevalence and severity. The Water Insecurity Coping Strategies Assessment Toolkit offers a comprehensive approach to evaluate these strategies and inform the design and monitoring of interventions targeting those most vulnerable to water insecurity.