Legionella Testing, if you are a landlord or business owner responsible for health and safety, may be something you are already familiar with. However, it’s surprising how many people aren’t aware of Legionella and the potential risks/ health hazards if left untreated.

What is Legionella?

Legionella Bacterium












Legionella is a bacterium found in water droplets, which when inhaled can cause Legionnaires’ disease, a potentially fatal form on pneumonia.

Unfortunately, all man-made water systems provide an environment where Legionella can grow. It is more common in systems like air conditioning and hot tubs.

The bacteria has the opportunity to grow in conditions where the water is stored and/or recirculated with access to ‘food’ for the organism to grow (rust, sludge, scale etc).

When should Water be Tested for Legionella?

Water Testing









The HSE have advised several situations that indicate testing should be carried out for Legionella:

  • Ideal temperatures are not always obtained (hot water should be hot and cold water should be cold)
  • The legionella control system is suspected to be inefficient.
  • If there is any doubt over concentrations of disinfectant in the system
  • Where the situation is deemed high risk for any other reason

Legionella testing of open systems (spa pools, hot tubs, evaporative condensers) should be undertaken at least quarterly. However, if the circumstances above arise, the testing should be carried out sooner.


How do you carry out Legionella Testing?

Legionella Testing












A sampling method is used, in accordance with BS7592 and the biocide. The water samples should then be tested by a UKAS-accredited laboratory that takes part in a water microbiology proficiency testing scheme such as that run by Public Health England.


Legionella Testing for Landlords

Risk Assessment













As a landlord you have a legal responsibility when renting out a property to ensure the health and safety of your tenants.

This means that you have a duty to assess the risk from exposure to Legionella, to ensure the safety of your tenants. However, an in-depth, detailed assessment is not required.

This is because typically domestic properties carry a low risk of Legionella.

If the simple assessment shows that there are no real risks, then no further action will be needed.

There are some simple measures you can take to help ensure the risk remains low:

  • Flushing out the system prior to letting the property
  • Setting control parameters (set the temperature of the hot water cylinder to ensure water is stored at 60 degrees)
  • Prevent debris from getting into the system.
  • Remove any redundant pipework.


Who can Carry out Legionella Testing?

Untitled design 2021 05 12T102023.061













Legionella testing can be carried out by a service provider, provided they are trained to do so and are properly supervised.

It is beneficial to hire a professional who has the knowledge and experience to conduct a full risk assessment and understands everything they are looking for.


For help with your Legionella Testing, contact Green Flame today.

For any additional information on Legionella Testing click here.