A group of 29 plaintiffs filed a lawsuit March 1 against the city of Alamosa, Colorado claiming salmonella bacteria in the water supply had sickened and even killed some members of their families. An investigation by the Colorado Department of Public Health and Environment concluded that salmonella from animal feces contaminated the drinking water supply in March 2008 for an entire week before being detected.

This contamination caused the worst waterborne-disease outbreak in the U.S. since 2004. In a city of 8,900 people, an estimated 1,300 Alamosa residents, almost 15% of the population, became ill. Department officials identified 442 cases of “probable salmonella infections” and acknowledged a cracked water reservoir as the likely point of origin. The lawsuit claims the water reservoir had cracks, noticeable holes, over 12 inches of sediment at the bottom, and had not been drained or cleaned since 1984.

The city of Alamosa had been exempted since 1974 from a state requirement to treat drinking water with chlorine, which kills salmonella bacteria because its reservoir draws water from deep underground wells. After the outbreak, the water system was flushed and disinfected with chlorine, a process that took more than a week to complete. Chlorination equipment remained in place following disinfection.

This example illustrates the importance of properly maintaining water storage and distribution equipment. While the Alamosa groundwater sources may have been pristine, it is likely that microbes infected the water as it resided in a reservoir that had fallen into disrepair. Inspecting water supply equipment frequently is essential. In addition, most U.S. water systems employ chlorine-based disinfectants for lasting residual protection from waterborne disease throughout the distribution system, including during storage.

For more information about the safety benefits of chlorinated water, please visit our website.

(Chris J. Wiant, M.P.H., Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council.)

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