Disinfectants for Water Treatment Against Legionella

Legionella is a type of bacteria that can cause Legionnaires’ disease, a serious lung infection. Legionella is found naturally in water, but it can grow and multiply in warm, stagnant water, such as in hot water systems, cooling towers, and humidifiers.

Water treatment Legionella disinfection is the process of using chemicals or other methods to kill Legionella bacteria in water systems. This is important to prevent the spread of Legionnaires’ disease.



Monochloramine is a disinfectant that is used to treat drinking water and control Legionella bacteria. It is formed by reacting chlorine with ammonia. Monochloramine is less reactive than chlorine, but it is more stable and persistent, making it effective for controlling bacterial regrowth and biofilms.

Chlorine Dioxide

Chlorine dioxide is a disinfectant that is effective against Legionella bacteria. It is a powerful oxidizer that can penetrate biofilms, which are slimy layers of bacteria that can protect Legionella from other disinfectants.


Chlorine is a versatile and effective disinfectant that is widely used in water treatment to control Legionella bacteria. It is a strong oxidizing agent that kills Legionella by damaging the cell wall and disrupting its metabolism.

Hydrogen Peroxide

Hydrogen peroxide (H2O2) is a powerful oxidizer that can be used to disinfect water and control Legionella bacteria. It is a broad-spectrum disinfectant that is effective against a wide range of microorganisms, including bacteria, viruses, and fungi. H2O2 is also effective at removing biofilms, which are communities of microorganisms that can form on the surfaces of water pipes and plumbing fixtures.

Chemical Disinfectants

Chemical disinfection is the most common method of Legionella disinfection. Chlorine, chlorine dioxide, and ozone are all effective at killing Legionella bacteria.

Chlorine is the most widely used disinfectant for water treatment. It is relatively inexpensive and easy to use. Chlorine can be added to water in the form of sodium hypochlorite (bleach) or calcium hypochlorite.

Chlorine dioxide is a more powerful disinfectant than chlorine, but it is also more expensive. Chlorine dioxide is often used in large buildings and industrial facilities where the risk of Legionella infection is high.

Ozone is a gas that can be dissolved in water to create a powerful disinfectant. Ozone is effective at killing Legionella bacteria, but it can also be corrosive to water pipes and equipment. Ozone is often used in combination with other disinfectants, such as chlorine.

Other Disinfectants

In addition to chemical disinfection, there are a number of other methods that can be used to control Legionella growth in water systems. These methods include:

  • Temperature control: Legionella bacteria grow best in warm water. Keeping water temperatures below 77°F (25°C) can help to prevent Legionella growth.
  • Physical cleaning: Regular cleaning of water system components, such as pipes, tanks, and cooling towers, can help to remove biofilm and other debris that can provide a habitat for Legionella bacteria.
  • Ultraviolet (UV) irradiation: UV irradiation is a non-chemical method of disinfection that can be used to kill Legionella bacteria. UV lamps are installed in water pipes and emit UV light that kills bacteria as the water flows past.

Water Treatment Legionella Disinfection Programs

Many buildings and facilities have water treatment Legionella disinfection programs in place to help prevent the spread of Legionnaires’ disease. These programs typically include a combination of the following measures:

  • Regular water testing: Water systems are tested regularly for Legionella bacteria.
  • Chemical disinfection: Disinfectants are added to water systems to kill Legionella bacteria.
  • Physical cleaning: Water system components are cleaned regularly to remove biofilm and other debris.
  • Temperature control: Water temperatures are kept below 77°F (25°C) to prevent Legionella growth.

Here are some additional tips for water treatment Legionella Disinfection:

  • Work with a qualified water treatment professional to develop and implement a Legionella disinfection program for your building or facility.
  • Make sure that your water treatment system is properly designed and sized for your facility.
  • Test your water system regularly for Legionella bacteria.
  • Maintain your water treatment system properly and promptly repair any leaks or other problems.
  • Train your staff on Legionella disinfection procedures.

By following these tips, you can help to protect your employees and visitors from the risk of Legionnaires’ disease.

Water treatment Legionella disinfection is an important part of preventing the spread of Legionnaires’ disease. By using a combination of chemical disinfection, physical cleaning, temperature control, and other methods, building owners and operators can help to keep their water systems free of Legionella bacteria.