Managing Risk: Preventing Legionella

Updated July 6, 2017: Recent Cases Underscore Legionella Exposure

Since we originally wrote this article there have been several new cases of Legionella reported where people have died and fell ill. In June, one person died and six became ill in the Lenox Hill neighborhood in New York where investigators are looking into the air-conditioning system for contamination as the source of Legionnaires’ Disease. In another incident, two guests at the Las Vegas Rio All-Suite Hotel & Casino contracted Legionnaires’ disease while they were staying at the resort in the months of March and April. Both the hotel and the Southern Nevada Health District were charged with investigating the two cases, remediating the problem and reaching out to past and current guests. They found that Legionella existed throughout the hotel’s water system.

In April 2014, as we first reported, Flint, Michigan switched its water supply from Lake Huron to the Flint River. The city was broke, and the switch was a way to save money. Unfortunately, the corrosive Flint River water caused lead from the city’s aging pipes to leach into the water. Anywhere from 6,000 to 12,000 children were exposed to high levels of lead and that can cause a range of serious health problems.

But we’ve heard that story, haven’t we? It’s been front-page news across America for over a year, and former President Obama even visited the city to heighten awareness on the issue. There’s more to this story though. As the water crisis unfolded, there was an outbreak of Legionnaires’ disease in the Flint-area that killed 10 people and affected another 77. An outbreak that many suspect might have been caused by the water supply change. Just recently, Nick Lyon, head of the Michigan health department was charged with involuntary manslaughter for the Flint water crisis.

Legionella is a type of bacterium found naturally in fresh water. When people are exposed to the bacterium, it can cause the potentially fatal Legionnaires’ disease and Pontiac fever. The bacterium grows best in warm water, like that found in hot tubs, hot water tanks, decorative fountains, and water-cooling towers.

People are exposed to Legionella when they breathe in mist or vapor containing the bacteria. Each year, 8,000–18,000 people in the United States are hospitalized with Legionnaires’ disease, and between 5% and 30% of those infected will die. In fact, the CDC reports cases have increased by 450 percent from 2000 to 2015.

Flint aside, Legionella is not just an issue for city planners or environmental bureaucrats. Owners of hotels, apartments, or commercial real estate should also take note: Legionella is a risk for people on your properties. For example, a hotel cooling tower caused more than 120 people in the South Bronx to contract Legionnaires’ disease in 2015 (12 of whom died). And, as stated above, most recently one person died and six fell ill just last month on the Upper East Side of Manhattan. Property owners and managers have a common law duty to exert a high level of care for employees and visitors to their facilities. Legionella has the potential to surface at any building. Many facilities harbor the bacteria in small quantities without issue, but maintaining proper standards and preventative maintenance of cooling towers and plumbing systems is imperative to keep legionella at bay to help lower risk of an outbreak.

Here are seven tips to help you prevent legionella contamination at one of your properties.

• Disinfect cooling towers regularly. At a minimum twice-yearly washout and cleaning programs should be in place, including oxidizing disinfectants.
• Disinfect ice storage chests in ice machines regularly.
• Store domestic hot water at 140°F and deliver it at a minimum of 122°F. High temperatures effectively kill the bacteria.
• If cold water tanks are located in direct sunlight insulate them in order to keep temperatures below 68; avoid locating them in sunlight if possible.
• Maintain anti-corrosion and scale prevention programs. Legionella thrives on scale and mineral deposits in water lines – especially warm water lines – so be sure that those lines remain clean. Use scale inhibitors where appropriate.
• Install and maintain high-efficiency mist eliminators on cooling towers. Many who contracted the disease were not in the impacted buildings at all, rather they were exposed to the mist that rained down to the street from the cooling towers.
• Control pH levels; pH between 5.0 and 8.5 are most at risk and regularly check the cooling tower for evidence of biofouling (accumulation of microorganisms, plants, algae, or animals on wetted surfaces). Legionella often use common amoebae or protozoa as host organisms, so by controlling the overall microbiological population, you can inhibit legionella growth.

As a property owner or manager, you should be taking all available precautions to ensure that your employees, guests, and visitors are only exposed to safe water sources. For more tips on how to do this, check out the Managing Risk Bulletin on preventing legionella.