The Impact of Chlorinated Drinking Water on the Infant Gut Microbiota: A Randomised Controlled Trial

Water chlorination is essential for controlling harmful microbes in drinking water; however, the antimicrobial effects of chlorine-based disinfectants may negatively impact the developing infant microbiota. This trial investigated the effects of chlorinated water on the infant gut microbiome. The waTer qUality and Microbiome Study (TUMS) was a double-blinded, randomised controlled trial. Six-month old infants (n=197) received either de-chlorinated drinking water via benchtop filtration (treatment, n=99), or regular chlorinated water (control, n=98) for twelve months. Tap water and stool samples were collected at baseline and at end of intervention. Metagenomic sequencing was used for faecal microbiome analysis. Primary outcomes were differences in gut microbiota alpha and beta diversity. Secondary outcomes included changes in the differential abundance of amplicon sequence variants (ASVs) and functional profiles. This study was registered with Australian New Zealand Clinical Trial Registry: ACTRN12619000458134.