Legionella is a risk when designing water systems.
Crystal IS
05/14/2019
Over the last few years, there has been a steady increase in drinking-water associated disease and outbreaks, particularly those caused by bacterial microorganisms. According to the Centers for Disease Control (CDC), a total of 42 outbreaks were reported across 19 states between 2013 and 2014. More than half of those (57 percent) were due to Legionella, a bacteria that has been determined by the World Health Organization (WHO) to be the most detrimental waterborne pathogen to human health in the developed world. While aging infrastructure and poor maintenance practices play a role in these statistics, pipes are not the only reason waterborne pathogens are on the rise.
Image 1. Example of a water system design (Image courtesy of Crystal IS)
A new report in Opflow by the American Water Works Association (AWWA) found that approximately 50 percent of all building water systems can harbor Legionella. These systems could include equipment such as water heaters and coolers, hot water tanks, booster pumps, beverage equipment, washing machines and even central heating and air conditioning systems. Therefore, the question around controlling for Legionella is no longer a hypothetical “if,” but rather a known risk that needs to be addressed within the initial design of building water systems.
This new challenge makes disinfection a critical part of water systems design. Both the pathogenic nature of Legionella as well as new guidelines from the CDC and the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) for specific applications of water use in buildings open up new methods of controlling risk at the point-of-use (POU), instead of using more costly point-of-entry (POE) systems.