Legionnaires Law: Cooling Towers Now Subject to Regular Inspection

In 1976, 182 Legionnaires came down with a severe case of pneumonia at a meeting of the American Legion in Philadelphia. Twenty-nine of them died—the cause of death was revealed as a new bacteria soon named Legionella pneumophila. Despite nearly forty years of research and mitigation efforts, however, Legionnaires disease remains a serious problem in highly-populated areas—now, Governor Andrew Cuomo and New York City mayor Bill de Blasio have rolled out a new set of rules designed to quickly identify and hopefully stop the spread of this disease. Here’s what it means for businesses.

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Why has legionella become such a persistent problem? The key lies in its growth medium: Water. Since any large building requires some kind of water supply and HVAC system, water is constantly moving through pipes, drains, and faucets before being sent into the municipal gray water system or used on site. But water also acts as the ideal home for legionella, especially at or just above room temperature—in fact, the bacteria is almost always present in small quantities. As noted by the Supply House Times, cooling towers used in large facilities make the ideal breeding ground for bacterial multiplication, since towers themselves are often contaminated with a host of biological foulants and outside water supplies are often little more than open sumps, the theory being that once pumped into a chilled environment most bacteria will be eliminated.

Dirty cooling towers, however, make it possible for legionella to work its way into potable water or water vapor, in turn infecting hundreds or even thousands of people. And while the disease is usually fatal only in the very young, old or those with compromised immune systems, both hospitals and schools make ideal bacterial breeding grounds, substantially increasing the potential risk.

Laying Down the Law

In New York state, Legionnaires has been making a comeback. Earlier this year the Bronx experienced a significant outbreak and as noted by ABC News 7, cooling towers in seven Long Island school districts recently tested positive for legionella bacteria. No illnesses have been reported and the towers were immediately taken off-line and cleaned, but the state is fed up with being one step behind this disease—according to the Voice Chronicle, New York lawmakers have drafted and passed a new law which should help reduce the spread of Legionnaires.

First, businesses are required to register new cooling towers with the state within 30 days. In addition, they must collect water samples and conduct culture testing within 30 days after registration, and repeat this testing every 90 days. The state also notes that companies must draft a regular cooling tower maintenance program by March 1st, 2016.

While testing and registration are excellent ways to monitor the health of cooling towers, regular maintenance is the only way to prevent the spread of this disease. Until the first outbreak in Philadelphia, many companies placed cooling system maintenance at the bottom of their checklist—if it was present at all. Solid maintenance schedules include regular tower cleaning and sterilization using a combination of effective chemical treatments and cooling tower washing equipment. Additionally, cooling tower basins need to be regularly inspected and cleaned of mud, sludge and other contaminants. If legionella is suspected or detected, all water in a system must be raised to 140 degrees Fahrenheit for 35 minutes, followed by a total system flush.

Legionnaires’ disease isn’t an easy problem to solve, since water systems naturally contain trace amounts of the legionella bacteria. New legislation, however, combined with regular maintenance has potential to speed detection, contain infection, and reduce the total number of outbreaks.

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One comment


  • Ive seen too many cooling towers be ignored. You are absolutely right in stating maintenance on them is virtually non existent. Water ignored in our business can turn into a huge problem. Regular water analysis and conditioning goes a long way.

    November 1, 2015

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