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How choosing tankless water heating can prevent Legionnaires’ disease

FOUNTAIN VALLEY, CALIFORNIAOver the past few years, our lives have been inundated with news and stories of the Covid-19 pandemic, overshadowing other illnesses that have spread across our nation. Another disease, however, continues to rear its head, sliding under the radar despite of its increase in cases.  

According to the CDC, the rate of reported cases of Legionnaires’ disease has grown nearly nine times since 2000, with 10,000 cases reported in 2018. But what is Legionnaires’ disease, and how can you prevent the spread of its potentially deadly bacteria? 

Let’s dive into the origins and the characteristics of this mysterious illness. 

Legionnaires’ disease and the history of Legionella 

On July 21, 1976, over 2,000 Legionnaires gathered at the Bellevue-Stratford Hotel in downtown Philadelphia to celebrate the bicentennial anniversary of the United States. This annual convention of the American Legion of Philadelphia resulted in a severe outbreak that would hospitalize 130 of its attendees, eventually claiming the lives of 34.  

The culprit? A strain of bacteria later deemed Legionella. 

An investigation by the CDC exposed a cooling tower on the hotel’s roof had been contaminated by bacteria. A water plume from the cooling tower drifted to the sidewalk below, descending upon the attendees and other pedestrians, causing an outbreak of pneumonia-like symptoms.  

This deadly illness later was coined “Legionnaires’ disease,” referring to the lung infection resulting from exposure to the bacteria. In time, the bacteria were identified and appropriately named Legionella.  

Exposure to legionella can also lead to Pontiac fever, a milder infection that can resolve itself without medical care. 

Signs and symptoms of exposure to Legionella 

Legionnaires’ disease is a severe form of pneumonia, involving inflammation caused by lung infection. Symptoms typically arise two to fourteen days after exposure to Legionella, but sometimes even longer.  

The most common symptoms include: 

  • Shortness of breath  
  • Chest pain 
  • Cough (may contain mucus and blood) 
  • Fever (can escalate to 104℉ or higher) 
  • Muscle aches 
  • Headaches 
  • Gastrointestinal symptoms (nausea, diarrhea, or vomiting) 
  • Confusion 

How does Legionella spread? 

Although the bacteria can survive in soil and water, most people are exposed when inhaling Legionella through microscopic water droplets, such as found in showerheads, sink faucets, hot tubs, swimming pools, whirlpools, cooling towers, decorative fountains, and plumbing systems, including hot-water storage tanks and conventional, storage-type water heaters. 

According to the CDC, a variety of internal and external factors can lead to a Legionnaires’ disease outbreak within a facility: 

  • Construction 
  • Water main breaks 
  • Changes in municipal water quality 
  • Biofilm 
  • Scale and sediment 
  • Water temperature fluctuations 
  • pH fluctuations 
  • Changes in water pressure 
  • Water stagnation 

Low amounts of Legionella in water do not lead to the disease. But when the aggressive bacteria find the perfect environment for growth, it can pose a major health risk. The bacteria must live within a specific water temperature range to grow, with a sensitivity to higher temperatures that will cause Legionella to die, disinfecting the water 

According to the American Society of Plumbing Engineers (ASPE), the ideal growth range for Legionella is between 90°F and 108°F, but the bacteria can survive in a wide range of temperatures: 

  • 68 ℉ and below — bacteria dormant 
  • 77 to 113 ℉ — growth range 
  •  90 to 108 ℉ — ideal growth range 
  • 118 to 122 ℉ — can survive but not multiply 

Depending on the strain, Legionella bacteria will begin to die over time when temperatures rise above 122 ℉, with the bacteria dying instantly at 158 ℉. 

How can tankless water heaters combat Legionella? 

Legionella bacteria is known to thrive in environments where warm stagnant water exists. In the case of traditional residential and commercial water heaters, or where external storage tanks are utilized, stagnation in temperature stratification can occur and create conditions conducive to the growth of Legionella. 

Take, for example, an application involving two, 1-million BTU boilers connected to a 1,000-gallon storage tank. When storage transfer pumps are idle, hot water rises to the top of the tank, while cooler water can be found down towards the bottom. Such a configuration may create an environment for Legionella growth and potential health risk. 

This is where tankless water heaters offer an advantage: minimum storage capacity and recirculation. Recirculation allows a steady supply of fresh hot water to be available quickly. An integrated or external pump allows hot water to travel from the tankless water heater to the desired location without excessive water storage. Also, in domestic recirculating systems, the recirculation process minimizes stagnation.  

But why not simply kill the Legionella bacteria by heating the stored water to 158℉ and higher? The problem is, with these temperatures, the risk of scalding increases. In fact, the risk does not outweigh the benefit. 

Let’s explore the newest commercial option from Facility Resource Group, a Noritz America partner, that can lower the risk of Legionella bacteria. 

TTS Synergy Series by FRG 

The TTS Synergy Series offers a plug-and-play setup with single connection point apiece for the water, power, gas, vent, condensate drain and building-recirculation lines. This rack system can combine two to six Noritz NCC199CDV Commercial Condensing Water Heaters with maximum inputs of 199,000 Btu/h, delivering more than 1,600 gallons of hot water per hour. 

Maintaining water systems with minimal storage and efficient circulation patterns can act as the first line of defense against the growth and spread of Legionella bacteria. For more information on what tankless water heater best suits your needs safely, contact Noritz here