A nose for trouble--the role of off-flavours in assuring safe drinking water

A detailed review of drinking water disease outbreaks over the past 30 years in 15 affluent countries produced over 70 case studies, some involving fatalities, which revealed a number of common factors in these disasters. Some of these outbreaks involved off-flavours, either as a driver for reducing disinfection and making the system vulnerable to pathogenic contamination or as an early warning of contamination that was not responded to with sufficient urgency or efficiency to avoid a disease outbreak. The characteristics of these outbreaks are recounted and the important link they reveal between aesthetically pleasing drinking water and safety is documented. Our analysis of common features in drinking water outbreaks also supports an argument that the failure of a water utility to be concerned about aesthetic factors makes such water supplies an inherently greater health risk for their consumers.