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Legionella Control and Why Temperature Monitoring is Important

Legionnaires’ disease is a potentially fatal form of pneumonia, contracted by inhaling airborne water droplets containing viable Legionella bacteria.

The bacteria thrive in temperatures between 20-45°C and where nutrients including iron and organic materials are available. The bacteria stay dormant below 20°C and do not survive above 60°C.  It is therefore vitally important to carry out regularly temperature checks on your water systems.

Your Legionella Control Legal Duty

Under the COSHH regulations, If you are an employer, or someone in control of premises, including landlords, you must take appropriate steps to identify and remove or reduce the risk of exposure to Legionella.

A Legionella risk assessment is required to demonstrate you have identified the areas at risk in your water systems and that you have a control scheme in place to manage the risks. As part of the control scheme, you must carry out regular temperature checks, which should be recorded in a logbook.

Key requirements for temperature monitoring

Temperature monitoring on domestic hot and cold water systems should be undertaken by competent personnel using the correct instrumentation. Temperature testing is normally required as follows;

  • Monthly temperatures at hot and cold sentinel outlets (near and far points on the water supplies)
  • Periodic monitoring of non-sentinel water outlets sufficient to show good temperatures throughout the water supply system on an annual basis
  • Temperature checks on cold water storage tanks in the Summer and Winter
  • Flow and return temperatures to hot water sources such as calorifiers.
  • Primary and subsidiary loops on larger supply systems

Remote temperature monitoring

If you are responsible for multiple properties, you may want to consider the advantages of installing remote temperature monitoring technology.

How it works

Remote temperature monitoring is a highly innovative and cost-effective way to manage multiple water systems. For example, if you have a number of residential accommodation blocks each with a water tank, these can be equipped with temperature probes which will alert you to any raised temperatures.

Each probe is linked to a central computer, which can record the data and flag up an alarm if results are outside the correct limits. It avoids the need for engineers to regularly enter properties to record temperature readings, a distinct advantage for sensitive sites such as healthcare facilities, care homes & schools. It is not intended to replace conventional temperature monitoring programmes, but can be a useful adjunct in many cases. 

The technology offer solutions in remote and difficult locations to ensure you meet current ACoP L8 guidance and regulations.


  • Reduces labour costs
  • Reduces manual site visits
  • 4G Wireless technology
  • Web based system accessible 24/7
  • Hot & cold domestic systems
  • Unlimited users
  • Email alerts for non–compliance
  • Produces monthly reports
  • Full audit trail
  • Daily trend analysis
  • Hardware and software supplied
  • Can be used alongside manual checks


If you would like to talk to our water hygiene team about how we can assist you with your water systems please contact or call Manchester 0161 872 7111 or London 0203 384 6175


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