Drinking water quality and enteric disease: a nationwide case-crossover study (2015–2019) in New Zealand

This nationwide case-crossover study investigates the relationship between microbiological water quality and enteric disease in New Zealand. Linking over 46,000 cases (2015-2019) to public water supplies, we found that E. coli presence, particularly in surface water supplies with known source risks and during high rainfall, was significantly associated with increased enteric disease risk. These findings provide novel evidence that routine water quality indicators may predict sporadic enteric infections, reinforcing the need for enhanced microbial monitoring and treatment, especially in high-risk supply zones.