A new Australian randomized controlled trial reveals that chlorinated drinking water exposure in infancy may enrich antimicrobial resistance pathways in the gut microbiome, even without disrupting overall microbial diversity.
Researchers from the waTer qUality and Microbiome Study enrolled 197 infants aged 6 months, randomly assigning them to receive either filtered de-chlorinated water or standard chlorinated tap water for 12 months.
While overall gut microbiome diversity remained stable between groups, infants exposed to chlorinated water showed enrichment of antimicrobial resistance-related MetaCyc pathways. The effect was stronger in infants who had previously received clinical antibiotics.
The findings suggest chlorine-based disinfectants may create selective pressures favoring microbial resistance functions during critical developmental windows.
Experts caution that water chlorination remains essential for preventing waterborne diseases, but further investigation is needed into how disinfected water influences early-life microbial development.