Protecting families from contaminated food and water
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Protecting families from contaminated food and water
Posted in Legionella,Legionnaire's disease,Our Blog,Outbreaks & Recalls on August 26, 2025
Rainwater in cooling towers following recent heavy rains are just one of the potential sources of Legionella contamination in Central Harlem building systems.
Some experts point to this phenomenon as the reason for the recent deadly Legionnaires’ disease outbreak in The Bronx. However, a key detail is being overlooked.
Proper, regular maintenance is designed to reduce these risks. Did cooling tower hygiene play a major role in this outbreak cluster?
What exactly is a cooling tower? How is Legionnaires’ disease spread by cooling towers? What could have prevented this outbreak? How do you know if you have Legionnaires’ disease?
Follow along for the answers to these pressing questions and more!
A cooling tower is a type of cooling system used in large buildings.
It works by removing heat from water at the end of the air-cooling cycle.
These systems work by blowing air over water to produce the cool air that comes out of the vents. Warm air is pulled back through the system and the whole process starts all over again.
Sounds simple enough.
This type of cooling system can be found in many different types of buildings around the world.
Some of the more common buildings include:
Unfortunately, cooling towers provide the perfect conditions for Legionella and other harmful bacteria to grow and multiply. Especially if they are left unchecked.
It is estimated that at least 60% of all cooling towers have at least some Legionella bacteria in them. However, some experts put that number closer to 80%.
When Legionella bacteria grow and hide in biofilms within cooling tower water tanks and lines, they can reproduce in a protected environment. As water moves over these microscopic structures, Legionella bacteria go along for the ride.
When they mix into the water and flow across the air current produced by the fans in the cooling tower that bring cold air around the building, those bad bugs can travel along the breeze and enter areas where people live, work, and travel.
When people inhale the contaminated air, they can become sick.
But how does Legionella bacteria get into the cooling towers?
Heavy rains introducing rainwater in cooling towers is believed to be a factor in the recent Legionnaires’ disease outbreak.
But how does that even happen?
For this, we will need to revisit the water cycle we learned in grade school.
Water in a stream or lake containing Legionella bacteria evaporates and becomes part of clouds. Some of those bacteria may be pulled up along the way. This is the “evaporation” step of the water cycle.
As more and more water accumulates in the clouds, these microscopic droplets of water begin to get heavy. This is the “condensation” step of the water cycle.
Eventually, heavier droplets form and come down as rain or some other form of water. This is the “precipitation” step of the water cycle.
As precipitation occurs, this water begins to collect again into puddles, containers, or back into bodies of water. This is the “collection” step of the water cycle.
Then evaporation occurs again, and the cycle continues on and on.
When Legionella containing precipitation makes its way into the cooling tower’s water system, it can introduce those germs into a man-made place that it doesn’t belong.
Aside from rainwater in cooling towers, other types of water contamination can occur to contribute to Legionella growth in cooling towers.
For example, if the actual water supply is already contaminated, the cooling towers will become contaminated.
This type of contamination happens when surface water is introduced into a water system. Broken pipes, untreated (or poorly treated) water, and other contamination methods can contribute to cooling tower contamination.
Any number of actions could have been taken to prevent this Legionnaires’ disease outbreak.
At a minimum, building owners are mandated by state law and city health code to test for Legionella every 90 days to avoid outbreaks. Additionally, periodic testing by the appropriate agency helps ensure that these systems are working. The Center for Disease Control and Prevention (CDC) says that the frequency of these tests should be adjusted based on performance indicators. If there is higher risk, this should take place more often.
The CDC indicates that buildings should undergo cleaning and disinfection per manufacturer recommendations. However, this should take place at a minimum prior to commissioning, before startup, when idling, and after shutdown. An offline disinfection should take place at least annually.
The CDC also recommends that the cooling tower systems operate at the lowest possible water temperature. Legionella bacteria grow best between 77 and 113° F. Keeping temperatures below that favorable range can slow harmful bacterial growth.
When cooling towers are shut down, even temporarily, they should be flushed. Additionally, any low-flow areas or dead legs should be flushed at least weekly, says the CDC.
Building maintenance plans should have contingency plans. Most existing plans account for water service disruptions, which could bring these units to an abrupt halt. But situations like rainwater in cooling towers should also be taken into consideration. Additional testing or disinfection activities makes sense in these scenarios.
If you have recently visited, worked, or stayed in an area with Legionnaires’ disease, you may be wondering if you have that illness.
While specific laboratory tests are required for an accurate diagnosis, you can monitor yourself for symptoms until the common incubation period is over. Most people begin feeling sick between two and 14 days after exposure. However, it can take longer for symptoms to appear in some cases.
Symptoms to look out for include:
Some people may also experience:
Most healthy individuals do not become sick when exposed to Legionella bacteria (the bacteria responsible for Legionnaires’ disease). However, certain groups of people are at an increased risk due to existing health factors.
While the infection can be treated with antibiotics, it is a serious illness. Most infected higher risk individuals will require hospitalization to make a full recovery and 1 in 10 will die from the infection. This statistic jumps to 1 in 4 resulting in death if illness is acquired while staying in a healthcare facility.
Common risk factors include:
If you have recently been exposed to Legionnaires’ disease and have been diagnosed with the illness in The Bronx, Central Harlem, or surrounding areas, you may have a legal case.
Legionnaires’ disease is a potentially deadly illness that can require extensive hospitalization. Medical bills and other expenses associated with the burden of Legionnaires’ disease illness add up.
An experienced Legionnaires’ disease Lawyer can help you navigate this difficult process and help you receive financial compensation for your illness.
If you wish to pursue a legal claim for financial compensation, The Lange Law Firm, PLLC can help. Call (833) 330-3663 or send us an email for a free, no obligation consultation. A member of our compassionate team will go over the details of your situation to determine if you have a legal case.
Call today to get the help and justice you deserve!
By: Heather Van Tassell (contributing writer, non-lawyer)