HSE Release New Guidelines Regarding Legionella

The Legionella bacteriais responsible for a set of several different pneumonia-like lung diseases that are collectively known as legionellosis. The most serious type of disease is referred to as Legionaires' Disease but Pontiac Fever and Lochgoilhead Fever are also caused by the same bacteria. The HSE maintains and updates as necessary the basic guidelines regarding the prevention of legionellosis in the U.K. They have recently released several new safety bulletins regarding Legionella prevention guidelines.

Legionella Testing and HSE Guidelines

Legionnaires' Disease is characterised by a suite of flu-like symptoms including coughing, muscle pain, headache and fever and chills. It may also produce less flu-like symptoms such as diarrhoea, confusion and rarely, pneumonia. A blood or urine test can differentiate Legionnaires' from the flu but this may not be done unless it known that there is a risk of Legionella exposure in the area.

In the period between August 2001 and August 2011 there were 44 outbreaks within the U.K., defined as two or more cases of legionellosis in the same area. Legionella bacteria are common in nature and are present in many lakes, ponds, rivers and other damp areas. However, the normal number of bacteria present is not high enough to cause problems. Most outbreaks of Legionella are associated with man-made water structures such as spas and cooling towers.

Situations that encourage the growth of Legionella bacteria include relatively warm but not hot temperatures (20-45°C), recirculated water and dirty water which is high in nutrients. People contract legionellosis by inhaling tiny droplets of water containing mass numbers of the bacteria which is why cases resulting from the low-level natural populations of the bacteria are rare. The HSE requires that business and landowners assess the risk of Legionellaon their property and take steps to prevent it if necessary.

Not all assessments will come to the conclusion that action is needed. However, failing to conduct an assessment is a violation of the law. Responsible parties who conduct an assessment and find no need for change are considered to be obeying the law.

One of the most recent HSE releases concerns the use of copper ionisation systems for the prevention of Legionella. Elemental copper has been used as a biocide in the past to remove Legionella bacteria from water sources. However, current support for this practice is minimal and the EU has made it illegal to use or manufacture elemental copper for these purposes. This law goes into effect 1 February 2013.

The HSE has also issued two additional safety bulletins in the 2012 year. The first was issued in July and targeted management personnel at cooling towers and evaporative condensers. The second was issued in September and urged employers whose businesses use water systems to conduct regular safety assessments and take steps to prevent Legionella growth. The bulletins also serve to remind employers that they are required by law to conduct these safety assessments.

Private landlords and others letting property are now required to conduct risk assessments for Legionellaas well. Previously, these individuals were exempt because water systems of 300l or less were exempt. This exemption has been removed and many organisations such as hostels, B&Bs, universities and private landlords are now responsible for conducting Legionella risk assessments.

Basic guidelines for the prevention of legionellosis have not changed. Assessing the risk of Legionella involves looking for some of these risk factors and then eliminating them as much as possible. Some of the steps to take may include:

  • Maintaining water at temperatures that are not tolerable to Legionella
  • Eliminating areas of stagnant water to the full extent possible
  • Controlling water spray to avoid aerosols
  • Maintaining cleanliness in the water and the entire system it passes through
  • Avoiding the use of materials which can encourage the growth of Legionella
  • Treating the water to kill Legionella or prevent it from multiplying


Open and closed systems have different risk factors since there must be an initial contamination by Legionella followed by a period of sufficient time to grow in order for there to be a health risk. Open systems such as cooling towers should be tested at least every three months while indoor systems may have a lower risk and consequently lower need for testing. The type and amount of maintenance performed on the system can also help determine the need for regular testing.

Author: +Duncan Hollis
AquaCert Legionella Testing