It's easy for those of us who live in "developed" countries to assume that our drinking water is safe. But the Salmonella outbreak in Alamosa, CO has reminded us – yet again – that we cannot take the safety of our tap water for granted.
The Salmonella outbreak in Alamosa continues to grow. The tally of reported cases has reached 216, of which 68 have been confirmed by lab test results. While municipal health authorities haven't recovered Salmonella from the tap water, they have found some bacterial contamination, and are taking no chances. The town is under a "bottled water" order, and the entire municipal water system is scheduled to be flushed and disinfected beginning tomorrow morning. The process will take several days.
Alamosa is only the most recent municipality to experience an outbreak resulting from contaminated drinking water. In 1993, residents of Milwaukee, WI were the victims of a massive outbreak of watery diarrhea caused by Cryptosporidium contamination in the municipal drinking water supply. More than 400,000 people are thought to have been infected by this protozoan pathogen.
The most appalling outbreak of gastrointestinal disease caused by contaminated drinking water took place in Walkerton, Ontario in 2000. This outbreak of E. coli O157:H7 occurred as the result of a convergence of environmental conditions (heavy rains), incompetence, government cost-cutting, and outright fraud. The events leading up to the Walkerton outbreak were investigated in a formal Commission of Inquiry, which issued a multi-volume report.
Walkerton residents became inadvertent guinea pigs in a study of the long-term effects of E. coli O157:H7 on a population. This small Ontario town has been the object of a prospective health study, which is entering its final year. Health care workers have been monitoring residents for kidney function, blood pressure, and other tests for the last seven years.
According to the CDC, 30 waterborne disease outbreaks were reported in 2003 and 2004. Seven of the 30 outbreaks – resulting in 1,830 cases of illness – were traced to improperly treated or untreated drinking water. The 30 outbreaks produced a total of 2,760 illnesses, and 4 deaths.
The United States and Canada aren't the only "developed" countries that have experienced outbreaks of gastrointestinal disease due to contaminated drinking water. Incidents have also been reported in recent years in numerous countries, including Denmark, France, Italy, The Netherlands, and New Zealand.
For more information on water safety issues, please see the CDC report "Tap Water - Where Does It Come From and Is It Safe to Drink?"