Water borrowing is consistently practiced globally and is associated with water-related system failures across diverse environments.

Water problems due to scarcity, inaccessibility, or poor quality are a major barrier to household functioning, livelihood, and health globally. Household-to-household water borrowing has been posited as a strategy to alleviate unmet water needs. However, the prevalence and predictors of this practice have not been systematically examined. Therefore, we tested whether water borrowing occurs across diverse global contexts with varying water problems. Second, we tested if household water borrowing is associated with unmet water needs, perceived socio-economic status (SES), and/or water-related system failures, and if water access moderated (or changed) these relationships. Using survey data from the Household Water Insecurity Experiences (HWISE) study from 21 sites in 19 low- and middle-income countries (n = 5495 households), we found that household-to-household water borrowing was practiced in all 21 sites, with 44.7% (11.4-85.4%) of households borrowing water at least once the previous month. Multilevel mixed-effect logistic regression models demonstrate that high unmet water needs (odds ratio [OR] = 2.86], 95% confidence interval [CI] = 2.09-3.91), low perceived SES (OR = 1.09; 95% CI = 1.05-1.13), and water-related system failures (23-258%) were all significantly associated with higher odds of water borrowing. Significant interactions (all p < 0.01) between water access, unmet water needs, and water-related system failures on water borrowing indicate that water access moderates these relationships. These data are the first to demonstrate that borrowing water is commonly used by households around the world to cope with water insecurity. Due to how prevalent water borrowing is, its implications for social dynamics, resource allocation, and health and well-being are likely vast but severely under-recognized.