In this new era of COVID-19, the idea of dealing with yet another deadly illness is a scary thought. Read on to learn more about Legionella disease and why you should be aware of it and, how to mitigate the associated risks?

Why Legionella is a concern now?

After months of no operation, many buildings and sectors have started to operate in half or partial capacity. This also implies that they have started to function building cooling systems and water heating systems to showers that had remain inactive during the time building was closed for operation and on pretext on winter season. When properties are closed for an extended period, for any reason, unsafe conditions can develop in building Cooling system. These can pose serious health risks.

Harmful microorganisms, particularly Legionella bacteria, can grow in the stagnant or standing water supply, which is a concern for safely reopening Cooling towers, and reopening floors at hotels and long unused rooms.
For all maintenance managers, the risk of Legionella could pose yet another big problem as it is as deadly and dangerous as Covid-19, and hence the ignorance may turn fatal.

The legionellae were originally transitory contaminants of environment but have since been recognized as natural components of freshwater ecosystems.

Fresh water used for air conditioning and plumbing systems has been left stagnant in many industrial buildings and businesses that were closed for COVID-19. When water is stagnant, hot water temperatures can decrease to the Legionella growth range (25–42°C, 77–108°F). Stagnant water can also lead to low or undetectable levels of disinfectant, such as chlorine.

The risk presented by Legionella is one of the tough challenges that facility and maintenance teams face on routine basis to keep their facility and surrounding area safe.

How is Legionella disease like Covid-19?

Like Covid-19, Legionella bacteria attacks lungs and is mostly caused by breathing in water containing legionella germ. Infection is acquired through breathing in aerosols (very fine droplets of water) which contain the bacteria.
Like Covid-19, people those are older or those who have weakened immune system are more prone to Legionella disease. Going by reports, both diseases have similar symptoms.

However, unlike Covid-19, Legionella is not a pandemic disease. It is not passed from person to person, nor is it acquired by drinking water contaminated with Legionella.
Also, Legionella is a bacteria, while Covid-19 is a virus. None-the-less, both poses high risk to life and need prevention.

Those at risk of exposure of Legionella, include not only those who work in the premises but also others in the vicinity. Facility team involved in handling Cooling tower may be at increased risk.

Most of legionella outbreaks could be prevented with effective water management and effective cooling tower water treatment techniques.

The most critical industry at helm of risk is Hotel and Hospitality sector and Hospitals. All buildings where Cooling Tower is situated at roof, or where people can be exposed to spray from the cooling towers pose very high risk of transmitting Legionella bacteria.

Hot water distribution pipe network via showers are also potential risk points as temperature is ideal for expended grow of the Legionella bacteria.

It will remain important for people to continue to take prudent steps to protect themselves and follow the recommendations specific to reopening after prolonged shutdowns.

Exposure to the droplets falling from Cooling tower can be avoided completely by paying close attention to the mechanical design of the Cooling Tower equipment or by treating the cooling tower water with new effective technologies.

In some countries it the legal requirement to carry out frequent risk assessments on cooling towers, to identify and assess any Legionella risk presented by the system, or any work associated with it.

Check to mitigate the risk of Legionella!

Ensure that your water system is safe to use after a prolonged shutdown to minimize the risk of Legionnaires’ disease and other diseases associated with water.

4 steps to follow before reopening buildings after prolonged period of inactivity!

  • Ensure that cooling towers are clean and well-maintained!
  • Ensure that the tower and basin are free of visible slime, debris, and biofilm before use
  • Treat stagnant water
  • Take monthly test for the Legionella bacteria

Old prevention techniques involve harmful chemical dosing in the Cooling Tower to prevent Legionella and other ills.

But how dangerous is it, exactly?

Is normal chemical treatment effective to destroy the Legionella bacteria ?

Handling & storing Chemicals for Cooling tower water treatment always remain a challenge. User is normally unsure on amount of chemicals to be added to get the best desired results. Normal oxidation of chlorine and other halogen-based chemicals at normal levels do not impose risk on equipment or risk of exposure in shower water, however studies shows that they are not 100% effective on destroying the Legionella bacteria. Super shock treatments are practically difficult to handle when the busing is occupied.

One proactive (and preventive) measure would be to choose the most advanced techniques to help minimize legionella growth. In recent years, the electrolytic disinfection process has gained popularity to offer a wide applicability in prevention of legionella bacteria and to treat Cooling Tower water for other ailments.

SBR – by CET ENVIRO is an Electrolysis treatment that comes with side-stream filtration. It is your cooling tower’s and hot water first line of defense against many issues. Without filtration, the solid buildups, airborne dirt, and pollen have the potential to foul and possibly halt the inner operation of any cooling tower water treatment. This type of scaling and fouling also gives room for bacteria such as Legionella to grow.
The electrolysis reaction is known to produce super oxidation power that is found to be very effective in prevention of the Legionella bacteria.

Amazingly, SBR Electrolysis system produces a mixture of oxidizers!

This includes free chlorine Ozone, Chlorine-dioxide, and free radicals. This is a strong combination to actually sterilize the water.

A water filtration system removes suspended and settled solids, which can help improve energy efficiency of cooling system and prevent health risks posed by waterborne bacteria. The use of electrolysis filtration system can also help in trouble-free operation and savings in maintenance costs. SBR does it all, without using any chemicals.

Click here for more information about SBR electrolysis technology!


Going by the reports, the cases and outbreaks due to legionellae are expected to grow in 2021 even as the world gets ready with Corona Vaccine. Especially due to building closures or reduced operations with fewer people returning to full-time building operations is expected during year 2021. The reduced consumption of water can cause water stagnation in building water systems, increasing the risk for growth and spread of Legionella.


COVID-19 is an emerging, rapidly evolving situation. Legionella is perpetual. As we look forward to life and work after the coronavirus pandemic, we should remain vigilant about Legionella disease and take preventive measures to reduce the extent of waterborne respiratory disease.

SBR Electrolysis system in action.

Top 5-star hotel chains in India implemented SBR technology in their top-line properties and it showed amazing results. Similar results were seen in other installations including leading mall chains, top IT hubs, pharma sector and hospitals.

If you want to immediately protect your Cooling Towers, hot water systems and the employees handling these systems from the HARMFUL LEGIONELLA BACTERIA, contact us for more information.

Click here to know more information on the Legionella preventive programs that we offer!