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Is disinfectant necessary for safe drinking water?

American Association for the Advancement of Science

A difference has emerged between some Western European countries and the U.S. regarding the use of residual disinfectants to offer safe drinking water. But who is right? In this Perspective, Fernando Rosario-Ortiz et al. compare the different approaches. To avoid microbial contamination, numerous countries including the U.S. and U.K. require the presence of residual disinfectant in drinking water. Yet the presence of a disinfectant can lead to the formation of carcinogenic byproducts, issues with corrosion, and an unappealing taste, the authors note. As well, there is little direct evidence that residual disinfectants have prevented drinking water-related disease outbreaks. A comparison of waterborne outbreak data from the Netherlands, United Kingdom and United States in recent years shows that the Netherlands has the lowest risk of waterborne disease, despite a lack of residual disinfectant use. The Netherlands, the authors note, has replaced more than half its water pipes relatively recently, while the U.S. and U.K. are running on a system comprising "expired" pipes; as pipes age, leaking and reduced pressure increase the chances of bacterial contamination. This may explain the difference among the countries, with leakage as low as 6% in the Netherlands, compared to 25% in the United Kingdom and 16% in the United States. Although more comparative data is needed, the authors note that the European evidence to date suggests that safe water can indeed be delivered without a disinfectant residual, as long as the right infrastructure is in place.

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