We sought to determine whether a shortened version of the 12-item Household Water Insecurity Experiences (HWISE) Scale, which measures water insecurity equivalently in low- and middle-income countries (LMICs), is valid for broad use. Using data from 9,261 households in 25 LMICs, subsets of candidate items were evaluated on their predictive accuracy, criterion validity, and sensitivity-specificity. A subset with items assessing "worry," "changing plans," "limited drinking water," and "inability to wash hands" because of problems with water (range: 0-12) were highly correlated with full HWISE Scale scores (correlation coefficient: 0.949-0.980) and introduced minimal additional error (root mean square error: 2.13-2.68). Criterion validity was demonstrated, and a cut point of ≥ 4 correctly classified more than 91% of households as water secure or insecure. The brief HWISE-4 can be used in LMICs to inform decisions about how to most effectively target resources and evaluate public health interventions.