How do you like your tap water?

Safe drinking water may not need to contain a residual disinfectant The expectation that tap water is safe has been sorely tested by the recent events in Flint, Michigan, where lead contamination has caused a public health emergency ( 1 ). Apart from contamination with heavy metals and other harmful substances, a key concern is the control of microbial contamination. To prevent microbial growth and protect consumers from pathogens from other sources, some countries, such as the United States, require the presence of residual disinfectant in drinking water. However, the presence of a disinfectant can lead to the formation of potentially carcinogenic disinfection byproducts, issues with corrosion, and complaints based on the fact that people dislike the taste of disinfectants in their water ( 2 ). The experience of several European countries shows that such residual disinfectants are not necessary as long as other appropriate safeguards are in place.