28 July 2017

Legionella prevention in hot water systems

Hot water systems provide the ideal conditions for legionella bacteria to multiply (bacteria are most active between 20C-45C.) How can you prevent the bacteria growing within your system?

Legionella prevention in hot water systems

Legionella prevention in hot water systems is an important topic for those with the responsibility for hot water system maintenance. 

Legionella is the bacteria behind the lung infection known as Legionnaires Disease. This bacteria can form in damp areas and sources of water, both natural and man-made, including hot water systems.


How does legionella form in hot water systems?

Hot water systems such as tanks and pipes are prime locations for the growth and dispersal of the legionella bacteria thanks to stagnant water. Poor maintenance of these systems can amplify the growth of this bacteria due to corrosion and the build up of scale deposits, which provide nutrients.

Any building which has a hot water system, or a water system of any kind, is at risk of legionella growth. Some establishments most at risk include:

  • Schools
  • Hospitals
  • Care facilities
  • Restaurants
  • Hotels  

Creating a legionella prevention plan

A comprehensive legionella prevention plan can generally minimise the effects of legionella and prevent Legionnaires Disease.


Risk assessment

The first step of any legionella prevention plan should be to carry out a risk assessment of your hot water system. This will allow you to properly visualise the possibility of legionella outbreak. Once you have carried out a full assessment you can begin to put controls in place.

When carrying out a risk assessment you should consider:

  • Temperature: bacteria multiply between 20-45ºC. They lie dormant below 20ºC and die above 60ºC
  • Nutrients: as mentioned above, limescale and rust provide nutrients, as well as algae and sludge.
  • Water storage: is water being stored or recirculated?
  • General water use: where is water consumed or dispersed?


Legionella control

Once you have identified the risks posed by legionella you can begin to put control measures in place. Control measures might include:

  • Ensuring correct temperatures: store and circulate water above 60ºC where possible to kill bacteria.
  • Reducing stagnation: not allowing water to pool can prevent the growth of legionella.
  • Keeping systems clean: clean and disinfect systems regularly to remove impurities and starve bacteria.


Testing regularly for legionella

By regularly testing for legionella you can identify the effectiveness of your prevention procedures. Testing can also highlight bacterial growth before it becomes a health issue. If legionella is identified further analysis should be carried out to inform required treatment.


boiler room equipment with pumps

The industrial chemical treatment for legionella

Often the only surefire way to prevent or treat legionella is with a comprehensive industrial solution. NCH Asia Pacific provides a full legionella treatment programme which includes risk assessment, analysis, chemical treatment and long term monitoring.

By enlisting the help of an industry expert like NCH Asia Pacific, you can fully meet your legionella management responsibilities without needing to carry out the complex, vital work yourself.

To find out more, visit our legionella treatment page, or contact us.


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