Practical tips to help you avoid a legionella outbreak

28 August 2013

There is a concern that because of rising fuel bills, and tightening budgets, that the advice given by the HSE for the prevention of Legionnaires' disease isn’t being correctly followed.


Residential and public buildings can both be susceptible to the legionella bacteria. The worrying thing is that home owners need to be aware of the potential risks of legionella, and ensure they check any work carried out on their homes is carried out by a competent person that adheres to the Code of Practice(L8).

Download our brochure for FREE now on 'Legionella the Management of Water Systems'.


Practical tips to help you avoid a legionella outbreak

Follow these tips to help avoid an outbreak:

Flush Little Used Outlets - Open tap or valve and purge to a drain without generating an aerosol. Purge until below 20°C or above 50°C (dependent upon the supply).

Check Tap Temperatures:

  • Open cold taps fully - Place probe/thermometer in centre of water flow for the full 2 minutes, check the temperature drops to below 20°C.
  • Open hot tap fully - Place probe/thermometer in centre of water flow for the full 1 minute, record the time it takes to reach 50°C.

Dismantle, clean and de-scale shower heads and hoses.

6 Monthly
Check temperature in the cold water storage tank.

Check for debris and sediment in the water storage tank.

Click here to find out more about Develop's C&G accredited courses


HSE Guidelines

Legionella can thrive anywhere as long as the conditions are right. The HSE has given the following 6 guidelines to prevent the spread of Legionnaires' Disease:

Ensure that the release of water spray is properly controlled.
Things like showers, car wash, high pressure hoses, cooling towers, toilets, all can spray droplets of water. All of these systems can create the environment for the Legionella bacteria to multiply.

Avoid water temperatures and conditions that favour the growth of legionella and other micro-organisms.
Legionella thrives at 37°C which is body temperature. Legionella will eventually die at 60°C, we therefore need to ensure we heat the water in our water heaters and boilers to at least 60°C. There has been a trend towards turning boilers and water heaters down to 50°C to save money energy bills, but this won't kill the legionella, it will just leave it dormant.

A basic Legionella Awareness course will give an awareness of Legionnaires' disease.

Ensure that water cannot stagnate anywhere in the system by keeping pipe lengths as short as possible, or removing redundant pipework.
In the workplace HSE risk assessments take place to ensure that pipework and systems adhere to the standard. The standard has been going through a consultation period that ended on the 23rd August, 2013.

For more information on all of the Legionella courses run by Develop Training click here.

Avoid materials that encourage the growth of legionella.
Because legionella needs to feed, you will need to make sure any of the material you use, is not corrosive to limit the growth of legionella. Ensure any installer you use is a competent person and sources all of their material through the Water Fitting and Materials Directory, the WRAS directory.

Click here for information on the C&G accredited courses that Develop Training deliver.

Keep the system and the water in it clean.
Regularly run the cold water systems until the water comes out below 20°C and hot water systems until the temperature rises above 50°C. Control the temperature and keep the water flowing.

Treat water to either kill legionella, or control its growth.
In systems where we can't use temperature as a means of control, we can use chemical treatments. You should always use a competent person to treat your appliances to ensure legionella is dealt with correctly. Some prime examples of where chemical treatments are needed are Hot-tubs; swimming pools and cooling towers.

Click on these links for more information Legionella Cooling Towers and Equipment and Other Risk Systems.


In summary

The amount of people being affected by Legionalla is on the increase, so it is paramount for the public health that these steps are followed. Just look at the links below to see how widespread this is becoming:

More information on the control of legionella can be found at

Discover which legionella course is right for you.. Download our free flowchart