Households in low- and middle-income countries commonly make use of multiple water sources. However, it remains unclear to what extent their drinking water choices are optimal from a health perspective. This matched cohort study across 10 islands in Vanuatu examined communities with both a groundwater and rainwater source to determine whether their preferred drinking option was the safest in microbial terms. In communities that preferred to drink rainwater, 56.5% of rainwater sources had 'high-risk' or 'very high risk' Escherichia coli contamination (> 10 MPN/100 mL) compared with 26.1% of groundwater sources (p = 0.092). Moreover, a preference for drinking rainwater was significantly associated with rainwater sources having 'high-risk' or 'very high risk' levels of E. coli contamination (p = 0.045). Results show that communities do not necessarily choose the safest water source for drinking. Findings also highlight the need to bolster local capacity to manage water quality risks and for Sustainable Development Goal monitoring to distinguish between protected and unprotected rainwater tanks.
Keywords: Pacific Island country; Vanuatu; groundwater; rainwater; water quality; water supply.